Okay, I have a iMac OS X 10.4.11, and I'm trying to plug in a regular microphone (Only way I can describe it is like a real life rockband mic) and I'm trying to record on Garageband. I bought 2 cords, XLR, which one plugs into the little jack next to where my headphones are, and one that hooks up to the Mic cord. I changed my sound settings to line in on system preferences but still no luck. What do I have to do to get this thing to work?