How is the human motor system organized?

I am looking for further information on the human motor system (as I search google, I do not get too many reliable sources). I do have the basic breakdown of the biological foundations and their placements with in the body, however I am looking for a more simplified source to help me break down the information (I am having difficulty understanding the layout itself). Please note that this is homework on a university level and I do not ask you to answer this for me, yet I do ask that if you have any reliable sources that I can use to further my research I would deeply appreciate it. Thank you in advance for your help.