Player, Pet, Target, Implied, Group, and Raid set

[Othesus]

It is complicated when you're first starting out. The best beginner guide is this one:
http://www.eq2interface.com/forums/showthread.php?t=858
The only information I would change is that you should only copy the eq2ui.xml file to your custom folder. You don't need to copy all the default files.

After that just start looking at all the other good mods that are available. Start with the simple single window ones and see how they work. The scripting is the most complicated and can take a lot of debugging and testing-- in the UI Builder and by loading up the game, checking something, quiting, fixing, loading, checking, quiting, fixing, about a hundred times.

If you want to edit the xml files directly I recommend using a text editor that understands xml syntax. I use Notepad++ with the xml plugin for all my editing and I don't think I could have survived using a normal text editor.