First, you need to state the units associated with the figure of 13.7; I assume you mean 13.7 grams.
Find the molecular weight (MW) of the substance in grams per mole. You can look up the individual atomic weights for the elements of the compound and get MW from
MW = (Cu) + (S) + 9(O) + 10(H)
Divide the mass in grams by the molecular weight in grams per mole. That gives you the number of moles of the substance.
Multiply the number of moles by Avogadro's number, 6.02 x 1023. That gives you the number of molecules of the substance.
Since there are 10 atoms of H in each molecule, multiply the number of molecules by 10 to get the total number of H atoms.