The marginal product is defined as the partial derivative with respect to the respective input.
In your case $\frac{\partial Y}{\partial L}=1.01 * 0.75 * ( \frac{K}{L})^{0.25}$ for labor and $\frac{\partial Y}{\partial K}=1.01 * 0.25 * ( \frac{K}{L})^{0.75}$ for capital.