yer you have it right now.

purchasing the domain simply allows you to trap requests to that address and then forward them to anywhere you like.

once you have the domain and hosting which supports ASP.net you are already to go. Just make sure you check some of their features such as maximum upload/download a month, the amount of space you get etc as you can get some very competitive rates. Generally the more you pay the better the service. Also check they are running the version of the .NET framework you require e.g. 2.0 or 3.5?