Need help understanding how to transfer MPQ files/folders

[Avalos]

I'm having problems downloading the MPQ model changes and getting them to work. I've looked for some tutorials but I haven't really found and clear ones. I've encountered .MPQ.rar files and I don't know what to do with the "Character" folder or whatever. As for other folders like Patch-Z.MPQ folder I don't know what to do with that. For the basic files I've downloaded some mount changes to see if it'd work and renamed them patch-7.MPQ or so and it is still not valid. I would like a thorough explaination as to what to do. Not "Unrar the rar folder and put it in the data folder".