Slap And Strum Technique!

Hey Ivan,
I really love your lesson and that's why I'm asking you to help me out. It's about two John Mayer song Stop this Train and The Heart of Life.
John use a weird technique that he slap a string and pull some others at the same time. I think I'm starting to get it right but it sounds way off.

There's a link where you can wacht him in action:

http://www.youtube.com/watch?v=-e1FHJkVoFE

If you could do something like a lesson or if you have some tips that could help me out, it would be awesome!
And thanks for your contribution to this site, it's really appreciated!

Hey Gmc!

Hi, my name is Martin and I am from Montreal, Canada, so my main language is french...( I try my best but sometimes I can make errors in my writing)

I'm in my fourth year playing the axe but I was playing on and off. Once, I didn't play for 6 months but I restart in the last couple of months. Maybe to the lack of amelioration. I'm probably the same player now than I was at the end of my first year.

My main inspiration is, and by far, John Mayer. I love the way he play, he can play fast, kind of SRV and with a lot of feeling. I love Bob Dylan too but he is not a reference in guitar .

So now I've register to GMC because I want to upgrade my skill. ( and for the John Mayer video that I saw here...God that guy who made the lesson is so good he sound just like him)

So lets play...