No fpm is punched into the autopilot. Either max take off thrust or a derate of up to about 20% is selected via the FMC depending upon the weight and environmental conditions. A V2 speed is calculated for the takeoff weight and entered in the MCP (autopilot) panel. After rotation the flight directors will command a pitch to give an airspeed of approx. V2 + 20 (about 150knots in a 737-700) this normally gives a rate of climb of between 2000-3000fpm and a pitch attitude of between 15 and 20 degrees.