homework and exercises - Guidance needed in finding scattering amplitude

If I have the Lagrangian

$$\mathcal{L}=\bar{\psi}(i\gamma ^\mu \partial_\mu - m)\psi -g\bar{\psi}i\gamma^5\phi\psi,$$ where $g$ is a coupling constant.

How to find the scattering amplitude for

$$\phi \psi \to \phi \psi$$ What I only learned in class was electron-electron scattering and electron-proton scattering and can't seem to relate this case above to any of them. I ask only for guidance. Please and thank you!