Blog Design Virgin

So I'm up early this morning, 4:00 to be exact, and start playing around with my blog. I found some new design stuff on Blogger and I think it looks kind of cute. But could someone please tell me what a "Gadget" is? I have no clue. Also, I know there are places you can get different blog designs to make your own, but I have no clue how. A little help, please?