C:\Windows\Microsoft.NET\Framework\v3.5\bin\csc.exe 
            /t:exe /out:MyApplication.exe MyApplication.cs

//all in one line
//or if that doesn't work try

C:\Windows\Microsoft.NET\Framework\v3.5\csc.exe 
            /t:exe /out:MyApplication.exe MyApplication.cs

//all in one line again