canon rebel t3i camera
Taking pictures
You can start shooting pictures right away with the exposure settings on automatic by selecting the green A on the dial on the top of the camera. Or consult the other sections of this tutorial for doing manual settings.
Autofocus and image stabilizer
Most Canon lenses come with an autofocus switch, and sometimes a switch for the image stabilizer. It's important to make sure the autofocus switch is set to AF to enable autofocus.
Conversely, if you want to manually focus a shot then set this switch to MF and use the front ring on the lens to bring a shot into focus.

The image stabilizer switch will enable a mechanism in the lens that helps to stabilize the image. This is especially useful when zoomed in on subjects far away while hand-holding the camera. The image stabilizer is not useful in situations when the camera is on a tripod, or you are taking mostly wide-angle pictures in well-lit conditions. The image stabilizer will use additional battery power to operate, so turning this option off may help to increase the shooting time.
Holding the camera
When taking pictures, you should always hold the camera with two hands; your right hand holding the grip with the shutter button, and the second hand with your palm facing upward under the lens. This is the best position for stability and reducing the chances of dropping the camera.

Keep your elbows inward, and feet spread apart – one slighting in front of the other – to increase stability.
Shutter button
The shutter button on the camera is actually two buttons in one.
You can press the button halfway down in order to prepare the camera for taking a picture. Holding the shutter button halfway down will activate the autofocus, charge the flash (if needed), set the exposure and prepare the camera for taking a picture.
Pressing the shutter button down completely will take a picture. If you press the shutter button down all the way without holding it at the halfway point first, it may cause a slight delay before the camera will take a picture.

