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'd like to show you a group that people spam in. https://gamehag.com/forum/dontwaste This is a group where people just randomly spam things. I think this group should be taken down and the people in it be banned, because they are just farming experience and soul gems in that group.