Well, you made your first post, so that's good! You know how to do that!
You can trade, by clicking on trade at the top. Since you made your first post, you can now send private messages! Add people by click on add friend at their profiles, click on send private message, or at the top, where it says, Private messages. Your profile, go to my account. Edit avatar, or signature, or add some interests. Do you have any pets? Go to adopt.

Ask me anything, I'll answer it! Welcome to CS, glad to help!