What is fusion and fission atomic

And what is nuclear fusion and nuclear fission, and atomic fusion is make two atoms came one, how won’t be done a big atom would be release a lot of energy and a normal size atom, the people don’t create new atoms, in the end the fusion would generate any atom of the atomic table and release a lot of energy, but if you want release energy destroying an atom you are talking of atomic fission, so in the fission the atomic energy is release energy destroying an atom. Rute Bezerra de Menezes Gondim