I want to shoot some sport pictures but i need to know what setting would be the best?

I have a nikon d3100 18-55mm. And i want to shoot some pictures for sports for my school year book. But i want to know what setting i should have the setting on so i can "freeze" the player. I plan to buy a new lense soon, any suggestions?

The easiest mode for you to shoot in will be shutter priority. You need a relatively fast shutter speed and good lighting (outdoors you should be fine) to freeze a player. For most sports you will need to use a shutter speed of 1/500th to 1/1000th of a second in order to freeze a player. Do a few experiments and you'll see how it works out for the type of sport you are shooting.

Take a look at a 70-200mm f/2.8 lens for sports. An f2.8 lens will let in plenty of light, which is good when you need to use high shutter speeds.

Shoot at shutter speeds of at least 1/500th second or faster

Use your light meter to pick the correct lens aperture.

Here is a sample of a shot taken at a high school football game. You can see what the settings were when I shot it.

Fast. That's all you need. At least 1/500s. Do everything you can, raise ISO (not too much or suffer from grain) and use a large aperture (smallest f/number). Position yourself at the back of the light source (sun or stadium lights). Get as close to the action without entering the field. Use a fast lens (oops, f/3.5 at 18mm won't be practical).