want to hook up my laptop with guitar amp to hear garageband effects

I have a MBP (early 2008) and use garageband with a blue snowflake microphone and headphones to record. However, I was wondering if it would possible to have my laptop hooked up to my Marshall MG10 CF amp when I am in garageband just messing around with the many effects that it offers and having the effects from my guitar come out the amp speaker (without having to use headphones. I hope my explanation is clear.