For the file waveSolver, you input how many grid points you want in each dimension and then it will output the number of time steps were taken, the x grid values, the y grid values, and the computed solution u(i,j,n) which gives the computed solution for u(x_i,y_j,t_n).
visualizeWave you input the output values from waveSolver in the exact order given and it will give a crude simulation of the solution.
normDiffWave gives the max-norm difference between two solutions. Input the fine x grid values, fine y grid values, and computed values on that grid. Similar for the coarse.
findN you give it a guess for N and then it goes on and finds.