transformation

i am making a game and wondering about movement of characters. I have a camera and monsters once i draw them i use timing function to move them, should i redraw them every frame on another position x,y,z or gltranslatef them, an also how to choose who i want to operate on?I have 20 monsters and i need specific one, maybe something with matrices or anything?It seems i missed or never found this info.Any help and EXAMPLE CODE would be helpful.Thank you.