Candling is the process of holding an egg up to a light source in order to see the inside of the egg and assess its viability. Here are the steps to candle an egg:

1. Gather your supplies. You will need a bright light source (such as a flashlight or a candling lamp), a dark room or closet, and the egg(s) you want to candle.
2. Turn off the lights in the room and close the door to create a completely dark environment. This will make it easier to see the inside of the egg.
3. Hold the egg up to the light source. You can hold it in your hand or place it on a flat surface.
4. Look for the shadow of the embryo inside the egg. If the egg is fertilized and developing normally, you should see the shadow of the embryo and its blood vessels.
5. If you do not see the shadow of the embryo, the egg may be infertile or may not be developing properly. You can also look for any signs of contamination or damage to the egg, such as cracks or discoloration.

It is important to remember that candling is not a foolproof method for determining the viability of an egg, and it is not possible to accurately assess the health of an embryo without a more thorough examination. However, candling can be a useful tool for checking the general condition of an egg and identifying any obvious problems.