How Do I add Car Nitro?

Im looking to increase my vehicles speed for a short amount of time using a gui.

I have no clue how to start.

I only know a few basics about scripting.

Why a GUI? Why not using a key bind? Well, for a GUI, you'd start with the clicked function. after that, increasing it's speed depends on how it's scripted, the easiest way would be to go to it's main part (of the weld) and add a bodyforce too it.