As Iam pointed out, there are two distinct types of blasting, one I refer as a grind for simplicitie's sake, and the other a blast. The grind is right hand on the hi-hat with the right foot, and left hand on the snare with the left foot. You then play a single stroke roll with your hands at whatever tempo you can muster. One either plays the one footed variety where the bassdrum only hits with the hi-hat, or the doubled variety where all four limbs are ostensibly playing a single stroke roll. The blast beat is one hand on the snare the other on the hi-hat with the feet either playing every note that the hands are playing, or twice as many, in a single stroke roll...hope that helps, and my advice is just to start SLOW and build up your speed and endurance SLOWLY.