User blog comment:Patrick.vtap/Mod Code/@comment-25612015-20150920192440

I advise you to start a mod of your own if your intent is to learn, because it is a little bit more difficult to make a submod, and the LOTR mod is very big which is not the easiest way to begin.

Anyway, it all depends on your programming experience.

If you are a beginner, you'll find Java a bit complex.

You might then want to try with Python and the RaspberryJuice Bukkit plugin (a Python interface to Minecraft). The "Adventures in Minecraft" book, by Martin O'Hanlon and David Whale, at Wiley, would guide you through it.

If you're already a programmer, and want to try Java, you can start a Forge mod (client side, for new blocks & textures) or Bukkit plugin (server side). The "Minecraft Mastery" book, by Matthew and Simon Monk, at McGraw Hill would provide just the information you need for modding. If you are more serious, go for the "Minecraft Modding with Forge" book, by Arun and Aditya Gupta, at O'Reilly, for a more extensive introduction to Forge modding.

There are also lots of tutorials everywhere on the Web...

When you have progressed, you will then be able to decompile the LOTR mod and start studying how you can use its classes and methods to extend it (there's no reason to include the mod's code into a submod).