Producers are plants. They produce their own energy using sunlight and the process called photosynthesis.
Herbivores are plant eating animals. All of the energy they use for survival comes from plants. In this image a rabbit is eating clover, a very common plant.
Some animals get all of their nutrition from other animals. This image shows a fox eating a rabbit. Energy from the clover fed the rabbit and the energy then went from the rabbit to the fox.
Omnivores like this opossum will eat plants and animals. Humans are omnivorous.
Top predators are primarily carnivores, but can be omnivorous like humans. Here a Red Tailed Hawk is about to grab an opossum. Energy to the top predators is the most concentrated.