Locate the atomic number of the element whose electron configuration you want to determine. You can find this on a periodic table. Technically, the atomic number is the number of protons in the nucleus, but in a neutral atom, the number of protons will equal the number of electrons.
Find an electron distribution chart or memorize the orbital levels and the number of electrons each can hold. The first orbital is marked "1s," which indicates that it is in the first energy level (1) and that it has a spherical orbital shape (s). The next orbitals continue as 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, and so on. S orbitals can hold two electrons, p orbitals can hold six, d orbitals can hold 10, and f orbitals can hold 14. When you write an electron distribution, include the energy level, shape, and number of electrons for each orbital --- e.g. 1s2, 2s2, 2p6, 3s2, 3p6, 3d10, which is the distribution for nickel.
Assign two electrons to the first level, 1s, giving you 1s2. Subtract two from the total atomic number so that you know how many electrons will go in the next level. For example, oxygen has eight electrons (atomic number 8), so two of those electrons will go in the first energy level, written "1s2," and six will be left for the next energy levels. For a hydrogen atom, the distribution will simply be one electron in the first energy level, written "1s1," because this element only has one electron. For helium, which has two electrons, it will simply be 1s2.
Assign the next two electrons to the first position of the second energy level, 2s, giving you 2s2. Subtract two from the remaining number of electrons. Assign the next six electrons to the second position of the second energy level, 2p, if needed, and subtract six from the remaining number of electrons. For oxygen, two electrons are already in 1s, so two more will go in 2s, and the last four will go in 2p. This gives oxygen the distribution 1s2, 2s2, 2p4.
Continue to assign electrons to the subsequent energy levels in order until you have no electrons left.