1. Install and set up Github Desktop: https://desktop.github.com/
2. Clone the repository to your .minecraft\resourcepacks folder: Code > Open with Github Desktop > Clone
IMPORTANT: the repository path should be .minecraft\resourcepacks\MusicfireRP (make sure there isn't an additional folder)
3. Once you've successfully cloned the repository, you can normally apply the resourcepack from Minecraft.
To update it as people add things, click on fetch origin and press f3 + T.
4. Add your item textures to the folder inside of assets that matches your area. Once you've added them, commit your changes and push to origin.
For anything that isn't item textures, contact the organisers.
A browser tab will open for it. Once created, an organiser will review it and add it into the main branch of the pack.