Help finding the guides I need?

[Corysia]

Wow...there's so many resources here, I'm not sure where to start looking. I want to write a patch to add a feature to one of my favorite addons. I'm trying to figure out where to get started. While I'm new to lua, I'm not new to software dev. I just need some pointers to find the resources I'm looking for.

Is there anything that describes the process of making a patch? Or is it best to just grab one and "use the source, Luke"?

Also, is there any offline testing tools or do I have to run ESO to debug?

Thanks in advance,
-Cory