Thank you :D, yea I was super confused how to use booster in the beginning too! The way it works is you send steem to them and that steem is put into a raffle with other people who bid steem too. They give out upvotes according to how much steem you sent, so if 2 people sent 5 steem and you sent 90 you will get 90% of the full power upvote.

To become a fan you go to the authors profile and on the top right side you will see a button saying Follow :)