How many electrons are in each energy level of Helium, Calcium, and Aluminum?

Helium:2p 2n 2e
Calcium:20p 20n 20e
Aluminum: 13p 14n 13e
Generally the n of electrons are equal to number of protons and are arranged in shells.
A shell can contain up to 2n² electrons; where n equals the shell number.
Every shell has 5 subshells s p d f g ...
Their energy levels are not ordered but they are mangled (see image).

so He 1s2, Al 1s2+2s2+2p6+3s2+3p1, Ca 1s2+2s2+2p6+3s2+3p6+4s2.
Al example says
1st shell s subshell has 2 electrons
2nd shell s subshell has 2 electrons
2ns shell p subshell has 6 electrons
3rd shell s subshell has 2 electrons
3rd shell p subshell has 1 electron
Total : 13, so 2+8+3 for the 3 shells.

Read my proposed source image for more, where you can find the energy levels of first n shells.
Note that every dot may have maximum 2 electrons (Pauli)