Where does one go to learn the ins and outs of creating a contribution to extend the core functionality of Zen-Cart? Is there a set of guidelines / rules about how to do this?
For example, I want to sell a product that required additional fields in the database to describe it. If I want to write and package a contribution to do this, where do I start to learn about it?
I've looked through the forums for "add-on" and "contribution" and can't seem to find any guidelines.