Most digital SLR cameras have a hot shoe for attaching a flash.
The Nikon D40x digital camera uses an accessory shoe mount, found at the top center of the camera body, to attach an external flash to the camera. The mount, also called a hot shoe, contains the necessary electronic connections to allow the camera body to relay information to and from the flash unit. It also secures the flash in place so it doesn't move around, something important to both lighting and the safety of a photographer who's moving around to take a picture.
Instructions
1. Hold the flash with its front facing the same direction as the front of the camera body.
2. Line up the flash's mount with the accessory shoe mount and slide the flash mount, starting at the back side of the camera and pushing forward. You will need to press firmly until the flash will slide no further.
3. Secure the flash into place using its locking mechanism, which will either twist or have a lever that pulls from one side to the other.
4. Turn on the camera and make sure the flash icon shows up when you look through the viewfinder.
Tags: camera body, accessory shoe, accessory shoe mount, flash mount, Nikon D40x, shoe mount