Well the space in which an electron maybe be found at each energy level e.g. s, p and d is determined by the wave function and is measured as a percentage. Can never be accurate due to quantum mechanical effects and in fact it could in theory not even be there at all.
S level orbitals contain up to 2 electrons in a sphere
p orbitals contain up to 6 electrons are 3 * 2 pairs along the x , y and z axis
d orbitals have up to 10 electrons in 5 *2 pairs in a range of Stange shaped orbitals. The d orbitals are actually split into 2 separate energy levels and this is why most transition metals can form nice coloured compounds