jitter SDK: filling a matrix

I am having a really difficult time understanding how to fill a matrix using the SDK. I know that the matrix data is flat, and i figured out (I think) how to fill a 1 plane matrix. But when it comes to multiple planes I am at a loss. I have looked through some example code, as well as the flop example by Nicolas Danet, but nothing is documented enough for me to get a good handle on things.

Could somebody explain to me, in very simple terms, how this is supposed to work? Maybe someone has a simple project that fills a 2 plane, 5x5 matrix with some values?

Thanks!!!