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.
About a week ago i installed Crossout, it took me about 2-3 hours before i got the 25 wins that are needed for the task. Then i realised that you can't see your total amount of wins, so the task is litterally impossible to complete. Maybe replace it with another task?