homework and exercises - How do you get quantum Hamilton-Jacobi equation from Schrödinger equation?

I am reading "The undivided universe: an ontological interpretation of quantum theory" and cannot understand this derivation.

From the Schrödinger equation: $$i\hbar \frac{\partial\psi}{\partial t} = -\frac{\hbar^2}{2m}\nabla^2\psi + V\psi$$ They derive the quantum Hamilton-Jacobi equation $$\frac{\partial S}{\partial t} + \frac{(\nabla S)^2}{2m} + V + Q = 0$$

using the polar form $\psi = Re^{iS/\hbar}$, but I don't understand what they do afterwards.