Steem power!! Steem dollars!! Steem!! What do all these terms actually mean??

Hey guys, here I am again but this time I'm not here to share anything but ask for something from you.

I am new to steemit and I just can't figure out what these obnoxious terms actually mean!!
At first I thought that steemit pays you every week but I think I was wrong because its been over a week and I still didn't get and steem dollars.

So if you could just help me with these terms and how they work it would be truly great of you.