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If the flash is TTL compatible with your camera, simply installing it to the hot shoe will do. Set camera to Auto mode with the flash to TTL mode.

If the flash is not TTL compatible to the camera, set the flash to Auto mode then set the camera to manual mode. Set camera also to 1/125s or whatever the maximum flash sync speed is and set to lowest ISO. Set the flash to the camera's ISO and check what aperture size it recommends. Set that on the camera. You should now be ready to shoot with the flash. If you find the flash too strong, step back. If too weak, move forward. That's it.

Mine just slid on.

You will want to adjust the ISO to the setting where it is darker than it looks. Then, the flash will fill the area.

The camera will not know that there is a flash, so you will have to do it manually