generating a system of linear equations

I want to solve a grid for the gauss seidel method and i need to generate equations for about 529 grid points. I know the boundary conditions. I need to generate these equations and put them in a matrix which i can use as the input for my gauss seidel or SOR code. Im very rusty at matlab since i havent used it in a while and i need help writing a small code for this task.