@retrolefty when i search i found that code for continuous rotation for arduino and so i used it. I knew about the servo library but i don't know how works. I will try again
@KE7GKP the max voltage for each servo is 6 Volt. My batteries are new and since i have seen many constructions with 4 AA batteries( 6 Volt) and 3 servos , i believe that it should work.