You could try using the "Time and Pitch machine" in the sample editor.
Open the sample editor, choose "time and pitch machine" and change the "transposition" parameter until you reach the pitch you want. The parameter box reads in cents, so one semitone = 100.
If you want to kep the original timbre/fomrants of the instruments, make sure you check the "harmonic correction" checkbox. Just bear in mind this will take a longer time to process.
Once you've got the pitch you're after, choose "process and paste" and wait...
Remember this is destructive editing so make sure you have another copy of the original tune (which you should already have if you've imported it.)
Another option is to convert the whole track into an Apple loop. Then you can change the key in the Global Tracks area as much as you like and the track will pitch up and down to suit.
Hope that helps, write back if you need more help