executing system calls in nachos 

hello i'm a new to OS. I have been given a task of creating and executing new system call for Nachos OS on windows. I was able to compile user programs under nachos/test . but while running user programs i keep getting the error
"COULD NOT FIND OR LOAD MAIN CLASS  nachos.machine.Machine" . I am using Cygwin Emulator for this task. please help me with this issue in a detailed and easy manner 
