Hacking ROM Hack How would I go about creating a texture hack for Mario Kart 7?

[ExperiencersInternational]

I recently stumbled across a video where people made some bad Wii texture hacks and I was wondering whether I could try making a (good) Mario Kart 7 texture hack (mainly with UI stuff, don't want to bother with text (characters), maps or 3D objects), but I don't know where to really start and how to organise the files in a way that Citra (and hopefully Luma3DS) would recognise it in the mods folder.

Any advice is appreciated