yay! Got promoted!

Hey everyone, I am pretty new on here so I'm wondering how you put an avatar up and what does it mean to "get promoted"? In the my profile section by the avatar section it says put in a URL. How do I do this? Also, how do I put the little pictures with sayings from the game at the bottom of my posts. I think they're called trophies. I know these are prob silly questions but if I don't ask, I'll never know. Thanx and have fun!