.mcw is the workspace file. When you have written your code, press the F10 button on your keyboard. This will verify the code to make sure there is no problems. When it successfully builds, it will generate a .hex file that can be found in the directory you are working in. Open IFI Loader, Click Browse, go to the directory of your code, and it will show up. Click the file, click open, and then click Download.
Enjoy
