It depends on the scope of your mod, there is a modding documentation folder in the darkest hour game files, and Hoi2 wiki has some modding pages that apply to DH as well. Most modding is just repetition the main difficulty for a beginner is navigating to the correct folders which can be confusing and frustrating at first but becomes second nature eventually. In regards to people not offering to help you'll find with this forum pretty much everyone is working on a mod and is tied up.
Some beginner tips:
> Download a good stable mod, NWO, Kaiserreich for example and learn from their style
> Use the guides in the modding documentation and those on HOI wiki
> When your stuck on something ask a specific question and you will get a specific answer it'll speed up the whole process
> Fire up the game after you complete every piece of work to ensure their are no unexplained crashes (don't do 3 hours work and find that the game crashes, you'll have no idea why)
> ALWAYS BACK UP YOUR WORK before you embark on a new series of changes