GMOD 13 multiplayer help

Ok so basically all I want to do is be able to select this option and then start the game, and invite my friend(s). Whenever I do that they can’t connect. Help would be very much appreciated. Thanks.

This means you are on a router and need to port-forward. Do a google search on portforwarding for GMod servers, they will give you a step-by-step guide.

Also, check your firewall.