Help me out a little bit... Steam is still confusing me.

Okay,

So I joined this awesome community of Steem Users.. I was given free Steem credit... I can vote up some posts, or write new posts. This is about all I have attained so far.

What benefit would I get by trading in some of my bitcoin for steem? (Is there a benefit?). Even when I vote for posts, my steem in my wallet does not decrease.

I am a little confused.. could you guys help drop some knowledge on my please :D

Thank you thank you!