Start with this introduction to the Arduino Uno Pinout: https://www.circuito.io/blog/arduino-uno-pinout/
Additional Hints:
"Pinout" means the mapping of physical pins to internal microcontroller functionality.
Many pins can do more than one thing. None of them can do everything.
The I/O expansion board in your kit will give you 8 more inputs/outputs. It connects to the Arduino over the I2C bus (using up two more pins!).
The Elegoo kit uses up almost all of the pins on the Arduino. You'll have to get creative and make trade-offs.