Specific heat is the amount of energy needed to heat 1 gram of a substance by 1 C. The specific heat of water is 1 cal/g*C. That means, if you give, say, 1 cal as heat to 10 grams of water, its temperature will increase by 0.1 C.

You should have see this formula in your physics/chemistry class:

where m is the mass in g, c is the specific heat, and is the temperature differential in C.

Replace the variables in the formula and you have the solution to your problem (remember, the temperature differential is negative, since the water looses heat!).