What happens next?

How to add explicit or clean tags in itunes with mp3tag (windows )
Convert all your files to. M4a files if they are not already in that format.
Itunes can do this. You can select all of your music files, right click, and click " create aac version.
" however, this option converts your music files and moves them to a different folder which you will have to hunt down. I would suggest downloading a different software, such as realplayer converter, which is free, to convert the files to.