The reason your server doesn't show up in the list is because it's not dedicated. As far as having your mate connect, once you know your ip, just let him know what it is and he can drop down the console (shift `) and type:
You probably won't need the port because the default (28070) is most likely being used. Just replace the x's with your ip. If you're on a different port just add
ort# at the end of the string--replacing the port# part with the actual number.