You actually get the compiler when you download the .NET framework and not the Visual Studio.
You can run the compiler from the command line, So assuming you have a very simple program in myprog.cs and you want to compile it with the command line compiler, you can compile it at the command line like this.
csc /target:exe myprog.cs
there are pleanty of compiler flags and you even need to include the names of the files you want to make use of in your program, so why not skip this one and use the Microsoft IDE.
i will come back here and give you all the command line arguments and everything some time later, for now i am not using this, it involves more typing than the progam itself.