On what computer operating system is your Premiere Elements running? And, what version of Premiere Elements are you using?
In the absence of details, I will generalize...
You are probably trying to use iTunes music in your Premiere Elements projects. If so, convert the iTunes music to a .wav file
in iTunes and then import the .wav version into Premiere Elements project.
With details, I can fine tune the reply for you.
Please do not hesitate to ask questions or to ask for clarification (however, details, please)