How i Found Booster PAcks

this post made me sad
you get them by collecting all the cards for a game and being lucky

This post gave me cancer. And I'm a robot.

okey sry i dont know it ^^

Earn all possible cards for a game and then a random chance to appear in your inventory each week (If a game has 8 cards for badge, but can only drop 4, you will be eligible after you get 4). I believe you need level 10 for them

There's a Steam Trading Cards FAQ, you should read that

Praise Gabe and every 10 levels you get 10% more chance to get one.