M Theory

I had a taste of M Theory in Stephen Hawking's "The Universe in a Nutshell", however to be honest I'm a bit confused as far as what exactly it says and means. If at all possible does anyone have a concise explanation of M Theory, Super-String theory and a synopsis of what exactly a p-brane and imaginary time is. I hate to sound as if I can't understand it, however without anything more that a high school physics class (which was not taught well at all and barely covered Newtonian physics let alone general and special relativity) and no college. If there's a link to the standard model (which accounts for the Higgs field) please explain that as well.