It's operated by a line that comes up through the cabin and passes through the deck just in front of the mast. Go up there and find it - follow it back towards the cockpit. It will run through a locking cleat that you will need to open. Put the line around the winch on the cabinet top and use a winch handle to raise the centerboard. When lowering, do it slowly and gently - there's no reason to just let it fall.
Congrats on the new boat.