I agree with Stephanie, Your best bet is to start by learning the basics of blender first...get the hang of what all it does because there's ALOT. I learned all about rigging and what not when I used to make cc for The Sims 4. I first learned by making stuff only in Blender...that really helped me understand how it works. Once I got the hang of DECENT clothes in blender then I moved on to using Marvelous Designer...and that way i had a better understanding of what to do once i had an obj imported into Blender from MD. This was a few years ago and I'm STILL learning...its not something that your going to learn over night. But that should be obvious haha
I know of some GREAT YouTube tutorials that really helped me out, Id be more then happy to share them with you if you want 🙂 message me in world, Evolava Resident, if you'd like!