This is a really thorough guide to getting your CSGO dedicated server to be hosted to the public, and show up on the server list (and so your friends can join from anywhere in the world). I made this to help others troubleshoot any problems they are having. It's almost always going to be networking mistakes that are preventing your server from being seen on the server list.
Timestamps are also included in the video, to save you guys some time. Hope it helps!
https://www.youtube.com/watch?v=PeclOEW8S4s