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.
they are most likely fake trust me i learned the hard way i had 400 gems and bought 2 chests. each cost me 200 gems and counting the one that everyone got for free at day of the blackfriday and i used them all in row only to get ruins and not keys therefore i can only assume that they are fake. so i advise you plz dont buy them instead save your gems for something else