How to Approach Monte Carlo Problem

I have an emag-related problem. "Consider the region enclosed on 3 sided grounded conducting planes with potential zero. It has width a in the x-direction and height b in the y-direction. The end plate on the left is insulated from the grounded sides and has a constant potential Vo. All planes are assumed in extent in the z-direction." Make a Monte Carlo simulation that results in a solution of the Laplace equation. How can I start to make such simulation?