My advise, from a noob also , is to understand what aperture, shutter speed and ISO do to a picture before you start shooting away on your new dSLR.

You also need to beef up your biceps due to the weight of a dSLR.

Be one with your camera and you will then be able to shoot better pictures.

Good luck!

Taking advantage of the VR, you can try shutter priority mode and set the shutter speed to 1/100s and then use maximum aperture at 200mm while keeping ISO at 800 or 400 if possible. Shoot RAW if you have enough memory storage as you can use adjust the exposure later should the pictures are not exposed properly.

The best is to be at the hall before the event starts and take some sample pictures while adjusting the camera settings accordingly.

Happy photographing!

When compared to a P&S, even a D40 is quite heavy for the untrained hands.

Even though you might be able to shoot 1/15s @ 200mm with VR, however, please understand what the TS intend to shoot. A 1/15s shot for graduation pictures will just produce useless blurred pictures. Do understand more before giving advise and this is my advise to you.