Check the forums here, there is a forum for addon lua/xml and tutorials and at the topyou find sticky posts with all info combined, and linked.
https://www.esoui.com/forums/forumdisplay.php?f=172
New to addon creation?
https://www.esoui.com/forums/showthread.php?t=9867
You'll find other devs to ask at the
https://gitter.im/esoui/esoui chat
If you are new to lua coding, read this first at best to understand it's simple mechanics:
https://wiki.esoui.com/New_to_lua%3F_GOTCHA
And here is a tut about writing your first addon:
https://wiki.esoui.com/Writing_your_first_addon
And a more experienced one using UI and XML too:
https://wiki.esoui.com/SimpleNotebookTutorial/part1