To a quick, yet thorough introduction to the 5D Mk III to get,

this DVD is a great help! A picture is worth a 1000 words but just ... This DVD is really well done, everything is well explained and above all shown, you get help for your own exercises (which you then should do if you want to have something like this) , and then you know the essential functions of the camera. It is not "lexical" procedure - ie not "Next comes the third function in the pull-down menu ..."), but it is a situational approach chosen so that it is immediately clear in what context you a or other option because needs.
In addition, there is a second DVD with some more specific clues that I can also highly recommend.