Before creating your own HUpack, you need to know what it is all about.

Hupacks is a resource pack, datapack and some content from HU. They are written quite easily

Now we move on to configuring the pack. A Hupack can be a zip file or a folder inside a .minecraft/hupacks. For working with packs, I would advise you to do this with a folder, and for publish hupack in zip. In the base directory of your hupack, you will need the pack.mcmeta file, which is also found in almost all resource packs. It should look like this:

{
    "pack": {
        "description": "My super-mega top hupack!",
        "pack_format": 6,
        "_comment": "By Chappie" // Dont needed but if u want do this
    }
}

The pack_format determines what MC version it's for.

That's all! You can now navigate to other pages to create your own content in your package!

And the wiki only describes how to write content that HeroesUnited adds (e.g. superpowers, costumes, layers, etc.). If you want to add vanilla content (recipes, functions, loot, etc.), there are tons of tutorials (and even generators) on the internet.