use the software that came with the player.
Or search the web for that players software. Type in players name and download it.
like the piece of junk mp4 player i purchased the mp4 file need to be converted to NXV format before you cand upload them to play on the player ,there for its not really a mp4 player ,there is a program on the cdrom that should have come with the player ,note =i took my piece of junk back to store ,
also i link in theis post for a converter .
I just got that MP4 player from Sourcinggate. It is also a watch style one and made in China. It is so amazing! Only you do is converted the file format to NXV format then you can upload them on the player. Trust me!
what kind of mp4 is that because i just got one from a pawn shop and no manule or instructions