To load your map change the "WM_part2_v004" to like blood_hospital_01 or AirCrash,
Then at the top of notepad, click "File - Save as".
Under "Save as type" at the bottom change "Text Documents (*.txt)" to "All Files" and change the "File Name" to Launch.bat
Once you have Launch.bat made, rename it to your map name and put it in the same folder as your left 4 dead .exe file. Double click .bat to launch game. You can also change the difficulty with this file at the same time.