Play games
Choose the game that interests you and play itfor free.
Complete the quests
Every game has some quests for which you will receive Soul Gems.
Receive rewards
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
I had some problems with pictures not uploading, in the end i got that 3mb is to big, so if it doesnt work for someone just try compressing it on some online program. (;