beginner looking for some help



I just recently got the monoprice mp mini delta and successfully printed the included lucky cat. and tried to set up wifi printing with it with varying results, since the included card was not large enough to hold one of the files I was trying to print so I bought a 16gb micro sd SanDisk. I loaded it up with both G-code and stl files my printer still saying that no files were on it. I could use any help you are able to give.