How can I take open shutter pictures on a Canon Rebel XS?

Have a look in your Instruction Manual...page 75, 'Bulb Exposures'.

I'm assuming your camera came with a 18-55 kit lens? That's a great all around lens for your purposes. If you don't have the cash, that lens should work well for your purposes. If you want a lens for sporting events, I'd suggest a 70-210 f4-5.6. I couldn't find a canon branded lens like this, but I know they should be out there from other lens makers, such as tokina, sigma and tameron. I'm a Nikon kind of guy, so I'm not overly framiliar with Canon gear. Good luck!

Open Shutter

If you will READ & STUDY your Owner's Manual you'll learn how to set your shutter to "B" - Bulb - which will allow you to keep it open as long as you want. Of course you'll need a tripod and the Canon Remote Switch RS-60E3.

Enjoy actually learning how to use your camera.

Put the camera on the manual mode and turn the dial until you see the B or bulb. On B the shutter will stay open as long as you hold the shutter button down. I suggest you use a remote or cable release to avoid any camera movement.

I also own an XS and I use the shutter control - see your manual.

You can set it to up to 30-seconds.