They would evaluate you first then go from there. If you want fatal1ty lessons he will walk you through basics, like movement,weapons,items, flick aiming etc at least that is how he trained some girls on his stream.

Slowly.

Give him a config, hardware, an account and instructions on how to use the site and friend list....

and let him play for 10 years in the same mod.

Setup.

Fix their monitor refresh rate/mouse hz / explain setup and get them a good mouse etc

explain about how to sit and hold the mouse properly

make sure mouse cord isn't dragging, get them 125+ fps in game and shit.

just the very basics

I'd tell him to keep his money and find him some equally skilled people to play with/against. Maybe ocassionally check his games and progression and give him advice. I'm not a robber, and besides, the logic/amount of experience I have wouldn't translate well to his limited amount of skill or knowledge about the game.