Where do i begin with creating addons?

Hey guys, Im looking to create a bunch of custom addons.

Im familiar with a few programming languages but i just cant understand the structure of addons.

Example: All the files inside addons, What files i need for certain gamemodes like TTT or creating DarkRP entities etc etc.

Im hoping someone could point me in the right place that will explain all of this for me.

Thanks in advance.

When in doubt, lua/autorun.

Seriously though you should get GMAD extractor and extract some addons you have, look at the file structure of those. Usually the main level folders will be like lua, gamemodes, materials, sound, etc.