There are several models of the Rebel. There's the t3, t3i, t5, t5i, and the xti. The self timer is what lets you take as picture of yourself. You set the timer (usually 2 or 10 seconds, press the shutter release and then run around in front of the camera. After the selected time, 2 or 10 seconds, the shutter releases and the camera takes the picture. The reason for using a remote shutter release or the self timer is to minimize the camera shake caused by pressing the shutter release. Since you don't have a remote or an intervalometer, you're limited to the self timer. This delayed release allows the camera to stop shaking caused by pressing the shutter release. If you have the instruction manual look up "self timer" or do a web search for "self timer how to" for the specific model you have. A cheap (they can be found on the river for just a few bucks) remote shutter release is a much preferred method for night photography.
OK, now for some night sky photography. Charge the camera battery! Turn off the autofocus. Your camera should have several exposure modes (T, AV, Auto, etc) Set the camera to Manual or Bulb (M or B) exposure. Set the shutter speed to 15 seconds. Not 1/5 second. Fifteen seconds. Attach the widest lens you have. Assuming you are using a zoom lens, zoom out to its shortest focal length. 50mm is good. 24mm is better. 16mm is very good. Use the largest aperature the lens has. Keep in mind that the aperature numbers on the lens are inverted. The smaller the number the bigger the aperature. You want to use the smallest number. Set the camera ISO to 3200. Mount the camera on your tripod. Aim the camera toward the south and about half way between straight overhead and the horizon. Press the shutter release. Continue until the batteries or you run out, Meteors are largely a matter of chance so most of your images won't have any. It will take about 30 seconds before you can take another photo. This is the noise reduction feature and it is normal. It's not unusual for someone new to night photography to panic when they can't take another shot immediately after taking a long exposure. Noise reduction doubles the exposure time. A 10 second exposure takes 20 seconds, a 45 second exposure actually takes 90 seconds, etc. This is normal.
Wide lens, large aperature, 3200 ISO, 15 second exposure should be a good starting point. Good luck! It helps to have a comfortable seat, something to drink and some snacks.
BTW, I recommend a basic digital photography course from a local community college for anyone just starting out.
