If iterations are independent, then OpenMP is the simplest way to go. On Mac OS X, you need to install gcc to compile with OpenMP, owing to the fact that the clang compiler does not support (for now) OpenMP. You can install easily a precompiled version of gcc from here:
You can also use MPI of course, but that is going to be much more difficult for you, (besides installation), given that you are not trained. If you want to stick with MPI, parallelizing a loop consisting of independent iterations requires computing for each process its initial and final iteration, managing data structures appropriately (remember that in MPI memory is not shared among processes) etc.