First soak up the liquid with something absorbent like a towel, paper towel, toilet paper, or the like. Then grab a new one and make it damp (water on it, then wring the excess water out). Then carefully wipe it clean. Then it will air dry.
You won't blow up your laptop just by pouring water on it but don't do the anyways since you'll ruin it.
They make special wipes for cleaning laptops and other electronics but you can just get a damp cloth (just wring out as much water as possible) and wipe off the chocolate. I got my electronics wipes at Staples for $5 - you can find them at other places like Target, Walmart, etc.