file locations

I have a quick question on file locations in C# - ie the physical location where you store your sourcecode.  In java the location of your file was dictated by the namespace which contained them.  In C# though, the namespace has nothing to do with file location.  So, if I wanted to store some of my source files in a different directory, how would I go about doing that?  

Would I have to compile them to a dll?

Thanks much!!!