You should see a folder (techCar) with the following three files.
techCar.ino (This is the file you will customize)
ElegooCar4.h
ElegooCar4.cpp
You should see the three tabs, one for each file, like shown below. Again, you will only need to edit the techCar file. The other two files are part of a library that makes programming your robot a bit easier, but you do not need to worry about them.
Click on Sketch > Include Library > Manage Libraries like seen below.
Once you are in the library manager search for FastLED and install it. Then do the same for ArduinoJson
You should see the process go through the following three steps, if successful.
Compiling sketch...
Uploading...
Done uploading.
