On your number pad (on the right side of your keyboard), click 0. That will switch you to camera view.
Hit N on your keyboard if you don't see this menu on your right hand side.
Lock camera to view
Reposition the camera : Zoom in or out: middle mouse wheel Pan side to side: Hold Shift & the middle mouse wheel Rotate camera: Hold down middle mouse wheel and drag
Rendering an image: If you want to render your scene, press f12. (Have patience as it renders) To get out of render mode, press ESC key