Can't start a server

Every time I try to start a server (nothing big, just for myself and my friends,) but ever since I cleaned up g-mod (as in re-naming the /garrysmod/garrysmod file,) the game starts a LAN game instead of an internet game. (I made sure that the checkbox that says “Lan” wasn’t checked.) Can any help me?

Have you checked your port configuration is correct?

sv_lan 0

When you say “port configuration,” what exactly do you mean? (I guess that means it is not correct.)

You have to forward your ports on your router in order to host a GMOD server.

How exactly would one go about doing that?

Instructions here:

You will never EVER see a game that is on YOUR LAN in the Internet tab. Ever.

Ask someone outside your LAN if they see it in the Internet tab.