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.
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
https://gamehag.com/forum/minecraft42 be the first ones to join the group, please there might not be a lot of people yet but I want you to change that and join now