It's actually not as complicated as it sounds. If you want to avoid blur, you need a high shutter speed. Sometimes some blur looks cool, but lets say you want to stop everything. As a previous poster stated, stay at a shutter speed of 1/750 or faster.
From there everything is related, and luckily it's pretty simple. As an exmaple of the relationship of the settings, let's say you are in automatic mode where the camera sets everything for you, and the camera's auto-exposure system is happy (says there is plenty of light) at a shutter speed of 1/1000, an aperture of f/8, and an ISO of 400. If you changed the ISO to 800, (which means it needs half as much light), the camera would either increase the shutter speed by one stop (to 1/2000), or reduce the aperture by one stop (to f/11). All three parameters are always related to one another.
Here's another example. For most sports pictures, shutter speed is important. Set the camera to some relatively low ISO (lets say 100), and select shutter priority. Set the shutter speed to 1/1000. The camera will now automatically set the aperture. If it's too bright outside (meaning the camera can't physically shut the aperture small enough to avoid having too much light) the camera will complain. If there is too little light (the reverse), the camera will also complain. You then have a choice of changing either the ISO or shutter speed to solve this problem. If the camera is happy, shoot away.
I'm probably rambling a bit here, and I need to run to a tournament game.
I'll end with this. When you select the camera's sports mode, the camera will essentially do this: set the shutter speed to a relatively high speed, then set the ISO and aperture to settings that allow a good picture to be taken given that shutter speed. It will also select a continuous auto-focus mode to allow you to follow the action and have the camera stay in focus, among other settings. You can implement the same sort of mode (if you prefer), with more control of the camera, by playing around with the settings yourself. Plus, you'll learn a lot about how your camera actually works.
Good luck, and post some pics to show us how you did!