Guitar sitting posture

Now,  its time to play,

Sit on a chair or preferably a stool, the idea is to keep your back straight and in an active position, now if you are a right handed person (most people are) then hold the guitar in such a position that the waist of the guitar sets on your right leg thigh and you have a good hold on the body of the guitar, now your left hand will press the strings on the fret board while your right hand will ring the strings.

Look at the image to gave you a better idea.
check out this video...