I like the tones that are on my synth, but how do I record them?

[tdubthatsme]

I have basically set up a recording using old gear my school had and was not using. The main issue I am running into is that I have no VI. However, I have a casio wk3700 synthesizer that has tones on it. How can I record when I play those tones? I currently am running through a firewire 410 to a macbook and using protools 7 academic version.
I tried directly plugging the 2 1/4" keyboard outputs into the 410's inputs in the back, but it didn't work.

I am basically teaching myself how to do this, and have run into this problem. Thanks for any help in advance. And sorry if what I said made no sense...