Here are some links for you to look into so you can see how to create an addon.
API Information Sites:
https://wowwiki.fandom.com/wiki/World_of_Warcraft_API
https://wow.gamepedia.com/World_of_Warcraft_API
http://wowprogramming.com/ - May not have been updated recently
Blizzard code can help you see how certain parts of the wow interface is created so you can learn how to make something similar.
Retail WOW
https://www.townlong-yak.com/framexml/live
Classic WOW
https://github.com/Gethe/wow-ui-source/tree/classic
This site looks to be a very basic start to addon writing so hopefully it will help you.
https://www.wowhead.com/guide=1949/w...ur-first-addon
Finally, have a look for an addon that does something similar and see if you can work out what each part of the addon does to use similar code for the same stuff in your own addons. Be aware of copyright and try not to copy someone elses addon, just use it as a guide to creating your own.
Good luck.