I only see ASP.NET 2 or 4 in my control panel. How do I enable ASP.net 3 or 3.5 Hosting?

ASP.net 3 and 3.5 are not true asp.net versions, they are just addons for asp.net 2.0.

So enabling ASP.net 2.0 in control panel will automatically include ASP.NET 3.0 and 3.5 features

The same principle applies to Asp.net 4.5.

Asp.net 4.5 is extension of Asp.net 4.0. Enable Asp.net 4.0 for website will support all features of Asp.net 4.5.