What's wrong with my science experiment?

If you used freshly made chicken broth, which had just been cooked on the stove, there were probably no living bacteria in it. They were all killed by the cooking. What you do is first make the agar by boiling the powder in water. You don't want any living bacteria to be in that. Pour it into the petri dish, cover it and allow it to gel (this will happen faster in the refrigerator, just like making Jello). Then you want to put some live bacteria onto the gelled agar. As I said, freshly cooked broth is not a good source of live bacteria. You can touch the agar with your fingers, or use a cotton swab (Q-tip) to wipe various areas like the sink drain, the bathroom floor, the inside of your mouth - areas where you know there are live bacteria. Then gently wipe the swab across the surface of the agar, cover the dish, and keep it in a warm dark place. You should have colonies of bacteria and fungi growing within 24 hours.