How do I get Sirius satellite radio at home?

I just got a new car and I get Sirius free for a few months. On the radio they always say to go online and sign up for an account and stuff. I looked around the site but couldn't figure out a way to sign up without having a credit card or something. Can I not use this feature because I don't pay for the service? Do I have to wait until my free trial is up and I start paying for it? Also, I plan on keeping it when my trial expires, but I don't want it only in my car, I want it in my house and stuff too... Can I buy a satellite radio or something and have it in both places? Or would I have to pay twice to have it like that? If so then I don't want it.. Can anyone help??