Hey Rob,
Do you have IIS installed on your machine? If you do, you have access to asp.net.
When you go to create a new project (in vb.net or c#), you'll notice the ability to choose an ASP.NET application. Thats all there is to it.
ASP.NET isn't so much its own language or component, as it is a new way to let your users access your code.
i.e. if you have a calculator dll, you can eitehr have a windows form reference and use it, or a web form to reference it and use it.
If you don't have IIS installed on your machine though, you won't be able to run/create any asp.net apps. You need a working web server to do it.
Hope this helps,
jack