Hammer the nail through the lid of the container to make a small hole, then light the candle and melt a drop of wax onto the hole that will form a seal when it cools. This will act as a safe pressure outlet to prevent explosion if gases build up inside the container.
Add mud to the container, filling to about 2 inches deep. Pour in pond water until the container is about two-thirds full.
Add about 1/4 cup of algae and small plants. Don't add large plants, fish, crustaceans, or insects that are found above the pond's surface -- they will more likely die in a small contained environment.
Place the lid on the container and seal it completely. Do not open it again until you are ready to discard the biosphere. The plants and animals inside the container will survive by making their own oxygen, carbon dioxide, and food within the closed system.
Place the biosphere container indoors where it will receive partial sunlight throughout the day. Direct sunlight can cause the temperature inside the container to fluctuate too dramatically.
Observe changes in the biosphere over the course of days, weeks, and even months. If plants die and the biosphere seems inactive, empty the container, wash it thoroughly and repeat the above steps to create a new biosphere.