You click on store -----> select the cheat and payment method (stripe) by clicking on the CS:GO account upgrade -------> Put your name, address, city, state, zip (if you are in a different country select your country and follow what it says) put the card number in
Ex: 2234222222 111 09014 <----- that doesn't work obviously.
And then click pay.
ex:
http://prntscr.com/nuv4x6