how do ..

There are 5 games in total in gamerage. If you sign up for a game which gamerage supports (expect from Crossfire EU) then you will get $10 free for that game which you can use.

You do NOT get $40 ZP for Crossfire NA/UK.
You do NOT get $40 on Crossfire Europe.
You do NOT get $40 in cash.

$10 gift on each of the four games which gamerage supports. Expect from Crossfire Europe.

Simple.