Well those are all different types of charges. Even in something as small as an atom, there are charges. Equal numbers of electrons and protons. The third particle is the neutron. A shell is sometimes called an orbital or energy level.
Shells are areas that surround the center of an atom.
The center of the atom is called the nucleus. As the electrons spin they can move in any direction, as long as they stay in their shell. The shell is the distance from the nucleus that the electron spins. If you are an electron in the first shell, you are always closer to the nucleus than the electrons in the second shell. Not all shells hold the same number of electrons.