Imagine a small pond contains 4000 g of water. If it absorbs 61.5 million solar energy in one day, and no energy is lost to evaporation, by how much will the water temperature rise?

If the unit of the energy is joules, then simply do:

Q = mcT

Q = 61.5M,
m = 4000 g,
c should given in the question and should be given in J/(gK) or else, you'll have to convert,
T is the change in temperature.

I suspect that the OP has a typo in his post - I'm guessing it should be 4000 Kg of water, not 4000g. Otherwise the temp rise of the water will be thousands of degrees!