Hey welcome. The official "Hi, I'm new" topic is stickied at the top of this very forum.
As for trading, you post your Haves/Wants, people reply to your topic. You read other people's Haves/Wants, you post on their topic. You and the other person come to an agreement on what is being traded and how (like who sends first (which probably be you since you have no references)). Then cards are mailed, they arrive, you post a Traded With post on the Good/Bad trader topic (and update it when you have to), and everybody is happy.