How to do electronic configuration?

Please clarify your question.

For writing electronic configuration of any element, please remember three principles which are
1) Afbau's principle which states that, filling of electrons will take place from lower energy level to higher energy level.
Now, to decide which energy level is higher, follow (n+l) rule ; where n = Principal quantum number and l = azimuthal quantum number
Greater the value of (n+l), more is the nergy.If the value of (n+l) is same then, the level with greater value of 'n' will have higher energy.
Thus, energy levels are in order:-
1S < 2S < 2p < 3S < 3p < 4S < 3d < 4p < 5S < 4d < 5p < 6S < 4f < 5p < 6p < 7S

2) Hund's Rule:- It states that pairing of an electron will start only if all the orbitals have each one electron in its subshell.

3) Pauli's Exclusion Principle :- No two electrons can have all four values of quantum numbers same in an atom.