To build a C# application from the command line, you will need to use the C# Compiler "csc" not nmake.
Step 1, download the .NET 1.1 SDK tools: http://www.microsoft.com/downloads/details.aspx?FamilyID=9b3a2ca6-3647-4070-9f41-a333c6b9181d&DisplayLang=en
Step 2, read up on C# compiler: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cscomp/html/vcrefCompilerOptions.asp
You might also be able to use one of the free C# IDE's, though you will need to recreate the project information.
You also need to make sure that while developing within the C#2005 IDE, you do not use any .NET 2.0 only classes.
Ronnie Wilkins, Jr.