What IP do I use when port forwarding?

I've correctly set up the port forwarding but I'm stumped on which IP do I use, am I using my Default Gateway IP or my IpV4 or is there some IP that I don't know about.

Let me explain a bit more, I was asking about trying to make someone else a certain character like a husk and with that command you provided me answered my question, thanks. https://cdn.discordapp.com/attachments/379136942882947084/383968237051969546/unknown.png Can you tell me how to set that one u...

I got a question, when you try to control a client it refers to a pop-up menu, Can you show me how to reach the menu as I can't find it B.