How can I use this with an existing adwords account? I went all the way through the signup proccess on the site I want to advertise on, but when I get to the end you have to create a new account, but I already have one
After you click the "advertise on this site" link select the option to log into your existing account instead of creating a new one. That doesn't always work. I've been talkig with the AdWords team about it for the past couple of weeks and they said they are aware of the problem and are working on it. Sometimes you have to click the "advertise on this site" link to get a CPM campaign going. If you just type the url in your account it will tell you the site is unavailable. Frustrating, hopefully it's fixed soon.
Thanks for the info. even i wasn't aware i can put url's instead of keywords. that makes me realise quite a potential for saving me money.