1 Answer

Which program are you using to try and convert the file? Are you sure it's compatible with a Mac? Does the program have a help or support button you can click?

Try these instructions 

Instructions
1
Select "Preferences" under "iTunes" in the top menu bar and click the "General" tab.

2
Click the "Import Settings" button in the section "When you insert a CD" and set the following settings:
"Import Using" is "AIFF Encoder" (use the drop-down menu)
"Setting" is "High Quality" (use the drop-down menu)
Box next to "Use error correction when reading Audio CDs" is checked

Click the "OK" button to save these settings.

3

Click the "OK" button in the "Preferences" dialog box.

4
Import your WMA file by selecting "Add to Library" under "File" in the top menu bar or by dragging the file to the Music library in iTunes.

Read more: http://www.ehow.com/how_5032617_convert-wma-aiff-mac.html#ixzz2gD4ciJdO