is your keyboard Midi? can it be connected to your computer via USB?
my guess is NO, but you can look at your keyboard and double check.
if it isn't, you'll need a midi keyboard. they're are few decent ones in the $100 range.
here's a good list (good site to buy from too, in my opinion)
http://keyboards-midi.musiciansfriend.com/midi
i have the m-audio keystation 49. it works great! be warned though, it's synth action, not weighted.