Obviously there is a confusion in your mind between .NET Framework
and Visual Studio
- .NET Framework is free and can be downloaded from Microsoft's website (your favorite search engine should tell you where to)
- Visual Studio is an Integrated Development Environment
that comes in several flavours ; some of them are free, the others not.
"Complete" versions (whether it is professionnal, premium, ultimate, etc.) are not free and can only be downloaded if you own a valid subscription to MSDN services.
There is an Express Version which is free and that you can download from here
Hope this helps.