Raise Your ISO to Get the Speed You Need
Ideally, you'd have a super-fast long lens (like an f/2.8 or f/4, right?) for your sports shooting, but those cost a bundle. So, how are you going to shoot sports with your f/5.6 zoom lens? By raising the ISO, that's how (see Nikon menu above). You can get away with 400 or 800 for most decent quality digital SLRs these days (the Canons, Nikons, etc.). That should give you the 1/640 sec. or higher speed you need to freeze the motion of sports without too much visible noise. Now, if there's enough light where you're shooting so you don't need to raise the ISOdon't do it. Preferably, you'll leave your ISO at 100 or 200 (or whatever the lowest ISO is that your camera allows), but in situations where your lens just isn't fast enough (which will probably be the case when shooting indoors with f/5.6 lenses, which are fairly common), you'll have no choice but to raise the ISO. You do that in the menu on the back of your camera (as shown here). Luckily, you can usually get away with an f/5.6 lens when shooting in daylight, but as soon as you move indoors, you're probably going to have to raise your ISO to get enough shutter speed to freeze the action. That's why fast lenses (f/2.8 and f/4) are so important to pro sports shooters.