How Do You Get Xbox Live?…

so i played call of duty mw2 at the mall on live for an hour. it was amazing! so i was wondering how do you set it up, do you need anything for it, and how to get an xbox live account.
thanks!

Suggestion:

http://www.xbox.com/en-US/Live/JoinLIVE/Home

You'll need a Gold membership to play online, which is $49.99 a year (~14 cents a day). Start off by making a silver account, and from there you have two options: using a credit card to buy your membership from the Xbox live marketplace or through the phone/online, or buying a gold membership card at a department store/entertainment store and redeeming the card on your dashboard.

Xbox 360 slim is completely wireless and only requires a wi-fi connection in your home.
Any older 360s need to be plugged directly into an ethernet port, either in the wall or on your modem/router. It's all relatively simple.