Maybe this was already what you were looking at, but this is a description I could generally follow.
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/mo.html
Bond order now is = (bonding electrons - antibonding electrons) / 2 = (8-4)/2 =2. “Although the Lewis structure and molecular orbital models of oxygen yield the same bond order, there is an important difference between these models. The electrons in the Lewis structure are all paired, but there are two unpaired electrons in the molecular orbital description of the molecule. As a result, we can test the predictions of these theories by studying the effect of a magnetic field on oxygen.”
Then use this for the answer for O2, though it seems like people are using slightly different notation for naming their orbitals.
Or maybe Molecular Orbital diagram for the molecule, oxygen, O2. - YouTube for a longer description (and there are others on YouTube).