HELP ! control servo-moteur

Hello, I like the project as the title says can control a servo by sending a sms via gprs shield. I when I send a sms "on" the front motor rotation is 90 and "off" to resume its original position. Being new to programming I really mess I do not really capture the AT commands and stuff .. So if any of you have a program similar to the one that I need I'm enormously grateful to him for letting me share thank you very much