I concur with Darnright. Alpha rolling, IMHO, is not a good way to go.
“Alpha rolling” is an ancient, debunked ‘training technique” that will at best, make your dog have a fearful, suspicious view of you and at worst, get your face ripped off.
It became popular with the gleefully sadistic “Koehler Method of Dog Training”.
Wild dogs do NOT “alpha roll” each other, ever.
Their ‘domination’ body language is infinitely more subtle and effective than that.
Find yourself some good books on dog body language and communicating with dogs.
http://www.dogster.com/lifestyle/dog-body-language-behavior-training