What version of Premiere Elements and on what computer operating system is it running?
If you have iTunes music especially, then you should take your file into iTunes to convert it to the WAV version according to the iTunes how to.
Then you import that WAV version into Premiere Elements project with Premiere Elements' Add Media (Get Media)/Files and Folders.
But, first try importing the music as is to determine if it will import with the need for the conversion to WAV version.
Please let us know your results when your schedule permits.
Add On...The answers are in the details. Once you give us the information requested above regarding Premiere Elements version, we can give you more information about the program.