First off, what is your level of musical training? Do you know how to read sheet music? Can you play any instruments already?
As far as learning keys goes, it's not all that hard. My advice would be to go to a music store and pick up a beginner keyboard book. That'll most likely get you the basics such as scales and chord shapes. Once you've got that under your belt, try playing along with the songs; it's a good way to develop your ear and learn the song at the same time.
But like I said, I'd get a book and go from there.
Good luck, man. Learning to play a new instrument is always very rewarding. I wish you lots of success!
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