Terry,
First, you need to make sure you're prepared for the written test. ATP should include in your course materials some sort of prep-course for the private written. Set a timeline for study with a firm date of when you want to take the test. This will ensure that you take the process seriously and study in a time-effective manner.
When you're ready to take the test, find a testing center near you. There are two companies (that I know of) that administer FAA writtens: CATS (all ATP locations are CATS testing centers) and Lasergrade (links to both websites below). They are usually located at FBOs and other aviation related centers. You simply walk in, pay a fee (about $90), and take the test. When you are finished, the results are printed, authenticated and handed to you. Once you start with ATP, you'll take the remainder of your writtens there.
As for housing, yes, it is included in the price of both programs. Definitely a nice feature of ATP's programs. Let me know if you have more questions!
http://www.catstest.com/
http://www.lasergrade.com/
>ML