The password on the bottom of the router is the router password, which is probably different than the router's wifi password. Connect to the router (with a browser on your computer) and look for the wireless page. Look in there for the wireless password.
In the phone, pick that connection. Tell it to "forget" it. It should find it again. Connect to it.
If you have problems finding anything in the router, boards.portforward.com has people who know the router, and they have pictures on the site of what the various menus look like, so they can take you through it.
