I\'m confused about AdMob. I just signed up and I want to put ads in an app. I went to add site/app thinking this was it. There is a question and field that says Android pac
When signing up for AdMob they want to see where your application currently is, but this isn't an essential part of the process from your point of view.
Basically, for AdMob (as well as a whole slew of other similar sites) you download a small SDK that you include in your Android application. This SDK usually has a View that you can plop on one of your Activities. You give that control some information, like a private AdMob key (so it knows which person you are) and then that control will provide an ad from the server. Note: it usually doesn't work right off the bat and there is a "development mode" setting you can set to always pull back a fake ad while you are just working on it.
You may also want to sign up for multiple sites and check out AdWhirl which allows you to manage the ratio of ads you display from each site, since you will find that some sites will generate more revenue for you than others.
Good luck!