Are you talking about sound and files in the MMM 16 Program or your projects and audio files.
If you want to transfer MMM 16 files then I think as MMM 17 License terms are different could create problem. As MMM 16 License is Royalty free while MMM 17 is free for home use for commercial usage need to buy extra license. If you still want to transfer files from MMM 16 to MMM 17 then there are many which one do you want to transfer? Soundpool or Synthesizer?
Or
If you want to import project and audio files then that is easy.
Open MMM 17 from File/Load project and browse your MMM 16 Project files.
For audio, open MMM 17 from File Manager browse Hard drive or CD/DVD/External drive. Locate files then drag and drop on arranger.
If you clear your question that will be helpful for anyone to answer ok.
If the MM-16 soundpool is still installed on your hard drive, they can be added to the MM-17 media pool just like any other. Click on the "Add styles..." link, locate the MM-16 soundpool styles on you hard drive and install.
As nihon94 said, be aware the the MM-17 soundpool has different limitations than the MM-16 soundpool when it comes to public/commercial uses.