I suggest you download a sample codeplug and look at its organization. I have some links to 9 sample codeplug sites at Amateur Radio but note the the MD-UV380 file structure is NOT the same as an MD-380.
If you opt to look at an MD-380 codeplug, you can make a structural conversion to the MD-UV380 file format by using the N0GSG DMR Contact Manager Support Page software. Be sure to read the PDF user manual first.
I have an MD-UV380. Perhaps the other notes and links will give you a jump start. Hope this helps.