please explain the flow of energy through a food web, and please explain the flow of matter through a food web

ENERGY: A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another; the levels in the food chain are producers, primary consumers, higher-level consumers, and finally decomposers. These levels are used to describe ecosystem structure and dynamics.

MATTER: When one organism eats another, the matter, or carbon, nitrogen, and other essential elements, are transferred from one to the other. These elements move from the producers, to the consumers, and eventually to the decomposers, cycling the matter through the ecosystem.

Explanation: look up

i do not get it   at all