Well, I don't know anything about C#, but I assume that Microsoft has some kind of official framework you can use. Otherwise I would suggest you go with Rails.

Well, I don't know anything about C#, but I assume that Microsoft has some kind of official framework you can use. Otherwise I would suggest you go with Rails. It's not necessarily the be-all-end-all of frameworks, but it's de-facto standard and has a very good ecosystem to use and learn from.