How to do port forwarding correctly?

Question

Computer networks

I need to open port 9090 via UDP protocol.
I don’t know how to fill in at all, on the screen below.

Answer 1

IP address - the address of the machine where to forward
Internal port - 2 fields: from __ to __ - that is, here you can specify a range of ports. In your case, fill in all 4 fields: 9090:9090
Do not specify the remote IP. This is something like a white list in this router, I think (but this is not accurate, each vendor of the field sculpts someone into something much), that is, if you specify, then only the connection will be forwarded from this address.

Answer 2

and you need a static IP (it changes for me)

This is for your ISP or some kind of dydns service.
For everything else, the picture clearly says where to write what.