Hi al2010. What specifically is confusing?
Sign up with a company - let's say Corporate International or MarketForce, as they have shops everywhere, and are a good place to start. After you've signed up, you should be approved - generally within minutes. Check your email for verification. Go, then, to their site (with your log-in and password, which you've noted) and search their job board for shops of interest, and of desirable proximity to you. Select a shop - almost any shop - just to get started, and either apply or self-assign, if permitted. You may have to complete training beforehand. Just takes time, choose training for a shop of interest. When you've been assigned a shop, thoroughly read the guidelines. When applying for a shop, you'll have to wait and watch your email to see if you've been assigned.
Come back with questions, at any step along the way.