Before editing the circuit we need to know some options and their functionalities.

Y.No	Name	Symbol	Description	Shortcut
1	View libraries		To search components in libraries we can open libraries using this option	–
two	Library Editor		It is an Eeschema shortcut option for the Library editor	–
3	Note		This option will help us assign sequence names to unnamed components in the circuit.	–
4	ERC		After finishing the circuit, check the electrical rules of the circuit.	–
5	Net list		After finishing our work on Eeschema, to continue working we need to generate a net list. This option creates a liquid list.	–
6	Generate BOM		Kicad can generate automatic bills of materials. After assigning suitable spaces to components, we can generate BOM using this option.	–
7	Edit footprints		If the footprints are not suitable for the components, we can use this option to edit the footprints.
8	New printed circuit board		By using this option we can associate components and footprints.	–
9	Add components		This is a shortcut option for opening libraries and for searching and placing components.	" A "
10	Power Symbol Selector		To add power supplies and grounding, we use this option directly when there is a need to search in a library.	–
11	Draw a thread		This is a shortcut option for selecting the wire. Wire can be used to connect circuit components.	“Z”
12	Draw a bus		This option will help us to add bus in the circuit	“/“
13	Draw wire for bus entry points		In digital circuits we need to connect wire to bus and bus to wire, these two options can be used to place entry points.	–
14	Draw the bus to the Wire entry points		In digital circuits we need to connect wire to bus and bus to wire, these two options can be used to place entry points.	–
15	Not connected		In the circuit, if we have any pins not connected, we need to add this option. Otherwise, in ERC it will be displayed as an error.	“Q“
16	Junction		If more than two wires meet at one point, we can place the junction using this option.	“J”
17	Local tags		If we need to connect the same network for different components, sometimes it is quite complex. In these situations, we can add labels. These are local labels that can only be used within a worksheet.	" I"
18	Global Tags		Global labels are also the same as local labels, but they can also be used outside the sheet. So we can put this in any spreadsheet.	“Ctrl + H”
19	Hierarchical Labels		It will connect the parent sheet and the remaining sheets.	"H"
20	Hierarchical Spreadsheets		If we are creating a very large circuit then we need a huge workspace, in kicad we can create and use different spreadsheets. Using this option we can place a sheet.	"S"
21	Import hierarchical labels		It is useful to place the imported hierarchical pin from the corresponding hierarchical label.	–
22	Place the hierarchical pin in the worksheet		By using this option, we can place hierarchical pins within the worksheet.	–
23	Graphic line		It will help to draw polygons.	“ “
24	Textual comments		By using this option we can assign text comments.	“T“
25	Delete		We can delete any component and network etc using this option.	Select component + Delete key

Fig. 1: Screenshot of KICad main window

Note: The table above contains only some commonly used and important Eeschema options. I haven't covered them all. Once you know these options, see more hotkeys by selecting the hotkeys option in the preferences menu. If any changes are necessary, we can also assign our own preferences.

I am selecting a circuit from Engineersgarage.com, which consists of 8051 microcontroller, 16×2 LCD, ADC0804 and some other components. Open the KiCad software and create a new project with a suitable name (Ex: EGtutorials). Open KiCad > File menu > New project > Name and save it. After creating the new project, we can see the project with subfiles on the left side of the KICad main window. We can see that the saved folder has a “.pro” file extension and in the subfiles the “.sch” file is a schematic file (Eeschema). Now we can start building the circuit. Open Eeschema and add components by selecting the “Add Components” option in the right toolbar. Or follow the steps. Eeschema > Press the “A” key > search for the component by typing its name > select the component. Ex: press the “A” key and a window with the libraries will appear on the screen. Many libraries are available like -74xx, -Atmel, – ADC-DAC etc. From these libraries, select the required component. If you want 16×2 LCD, enter the name and search. If you find it, check it and add it to the spreadsheet. If not found, create 16x2 LCD using library editor. Repeat the same procedure unless all required components are obtained. In the selected circuit, all these components are available except ADC0804. Actually, other series of ADC is available, but ADC0804 is not available. ADC0804 is a 20-pin DIP IC. So I'm going to create it in the library editor. Note: In the previous tutorial, I explained how to create a component in the library editor. Please follow the same procedure here. Steps to edit the component: 1. See datasheet for pin diagram. 2. Open the library editor > click “create new component” > name it ADC0804. 3. Click on the Place Pin option > assign a name and number to the pin > select the electrical type of the pin > click “ok”. 4. Repeat the same procedure up to 20 pins. (caution: be careful when selecting the electrical type of the pin) 5. Position the graphic rectangle that touches all the pins. 6. Save the component in the library folder. 7. Close the library editor > open Add Components > select ADC0804 > place the component in the spreadsheet. Now we have all the components. Place the components correctly (as per convenience) and select “place wire” to connect the components. I am connecting 16x2 LCD pins to microcontroller connections directly with wire. To connect pins 1, 2 and 3 of the LCD, we have to overlap some wires or else we have to connect using very long wires. So in this case I'm using Nets and Local labels. (Watch the video tutorial to understand better). Similarly, I am also connecting potentiometers. The pot has three prongs; one pin is connected to Vcc, another pin to ground and the third (middle) pin to LCD pin 2. Similarly, one more potentiometer is connected to pin 9 of ADC0804. In the same way, I also made capacitor and resistor circuits. Use local labels to connect ADC connections (name the labels carefully). After completing all connections, connect the power supply using the local “Vcc” and “GND” labels as well as the global labels. If we need this supply, we can also use it in other spreadsheets. Also, place “not connected” “ ” on each unconnected pin of the circuit. Note: When connecting the circuit, use the shortcut to move the component, place labels, etc., this will save your time. After completing all connections, edit component values ​​such as resistor values, capacitor values, etc. and “write down” the circuit. Noting is nothing more than assigning names to the components, for example, if we use 10 resistors in our circuit, initially, each component has the same name like “R?” If we leave these components with the same names without assigning different names, we will definitely get confused when editing the PCB. Therefore, writing it down is very important, don't skip it. Precautions: 1. When connecting the wire between components, please observe and connect them correctly. If it is not connected properly, we will get errors in ERC. 2. Assign names to labels selectively. 3. When creating a new component, be careful with the electrical type of the pin.