Well, the first thing you ought to do is to multiply 0.1 L by 0.10 M. That way, you'll find out how many moles CuSO4*5H2O were there.
0.1 L * 0.10 mol CuSO4*5H2O / 1 L
Then, multiply the thing by its molar mass.
0.1 L * 0.10 mol CuSO4*5H2O / 1 L * 249.68 g CuSO4*5H2O / 1 mol CuSO4*5H2O = 2.5 g
