When I try to set a waypoint, I have to do the specific setup:
#wp s tag name
but I don't know what a 'tag' is, and how to use it... help?

A tag is like an user-defined ID, just like a name with less letters, I think it's that, I still haven't experimented with waypoints but try around.

Tags are used to categorize your waypoints all tags can be found in this file

ty!!

In 1.12, there's tab completion too if you don't remember the tags.