Do not modify libraries that are shipped with kicad. Your modifications would be overwritten on the next update of the libraries. Make your own personal libraries.
I have written a few tutorials that could be useful for you. Currently i only have some for the footprint side of things.
- Creating a new footprint library (This one explains how to get a footprint into a new lib such that you can modify it.)
- Tutorial: How to make a footprint in KiCad 5.1.x (From scratch)?
As you come from a different software, you might also be interested in how kicad makes the connection between footprints and symbols.
- How does KiCad know which symbol pin represents which pad of the footprint?
- How can i assign a footprint to a symbol?
For the symbol side of things first create a personal lib (if you do not already have one)
This is done in the symbol editor. There are 3 options:
- File -> New library
- Button in the top toolbar (the leftmost button)
- Leftclick in the left sidebar -> new library
After using one of the options you will be asked where to save the library under what name. Depending on your needs either save it in the project directory (for project specific parts like a specialized connector or if you want your uC to have project specific pin names) or put it into some central space of your choosing. (Any storage area where you have write access will do.)
After giving the storage location, kicad will ask you if you want to add the newly created library to the global or local library table. (global means all projects will have access to it, local means only the current project will have access to the library. The later makes sense if you have stored the lib inside the project directory, the former if you stored it somewhere else.)
After that your personal lib should appear in the left sidebar. You can now add new symbols to it by left-clicking on the library name -> add new symbol.
If you want to store a modified version of some symbol found in another lib in this lib simply navigate to your source symbol (the filter field on the top of the toolbar will be of great help here). Left click the symbol -> copy. Navigate to your target lib, left click its name and choose paste.
To change a symbol name you need to edit the “value” field. This can only be done in the symbol view.
Open the symbol by double clicking it in the left toolbar. The symbol will now be shown in the large canvas area. You should see a text field with the same content as the symbol name somewhere on the canvas. To rename the symbol you need to edit this field. right click it -> edit. (or use the shortcut e)