If you are going to be using C# within ASP.NET (that is, *NOT* C# as a stand-alone, create-a-windows-".exe"-executable product), then by far the best place to start is simply
Assuming you will be doing web forms (likely, if you are using ASP.NET) you might start here:
Or maybe something like this:
The site used to be better organized. Used to lead you through the tutorials in a useful order. But Macro$loppy just can't ever leave anything that works alone. They always have to "improve" their web sites nearly into unusability.
Same thing with MSDN. But here's one good starting spot with MSDN: