. . . . How do i import my 3gp files from my cell phone into mep 2016 plus? . . . .
You are going to have to convert or rename the video files to a format that MEP can read.
Copy the files from the phone to your PC using Windows Explorer - you will have to consult your phone manual or manufacturer for the specific location where they are stored.
3GP files are basically mp4 files so you can try changing the file extension on a video clip from 3gp to mp4 and try importing it into MEP. See here to enable viewing file extensions and how to change them.
If this does not work, then you need to use a converter to extract the video into a format that MEP can read. there are many free converters on the Internet - however do be careful which you choose - some come with attached 'spam/advertising' options.
One of the most popular and effective is AVC - however you use at your own risk.