If you don't have a copy of your manual, you'll want to download a copy. You can get it from this page: http://www.usa.canon.com/cusa/support/consumer/eos_slr_camera_systems/eos_digital_slr_cameras/digita...
The instructions are on page 49 -- but really you should ready through the manual. You'll learn a lot of capabilites of the camera that are worth knowing that you'd likely miss if you don't read it.
There is a button on the back of your camera near the right edge of the LCD screen and it has an icon of a clock. If you press that button, you can use the left/right arrows to enable the self-timer.
It's a 10-second self-timer but it also puts the camera in a mode which allows it to be triggered via Canon's IR remote.
the current remote (which still works with your camera) is the Canon RC-6... it's not expensive -- just one button and it triggers the camera via IR.