[Winga]

There is no electron density around those atoms. That's the whole point of a node.

[Winga]

So, where are these 2 electrons?

I think they shoud be in the ring and occupied in certain orbital(s), right?  

[Mitch]

They are shard with the non-nodal atoms.

[Winga]

They are shard with the non-nodal atoms.

You mean the 4 carbons shown with p-orbitals?

After the each pair of p-orbitals overlaps to form 1 pi MO and 1 pi* MO, as the pi MOs are full-filled, so, are the 2 electrons filled in these 2 pi* MOs?

[Mitch]

You mean the 4 carbons shown with p-orbitals?

Yes

After the each pair of p-orbitals overlaps to form 1 pi MO and 1 pi* MO, as the pi MOs are full-filled, so, are the 2 electrons filled in these 2 pi* MOs?

I don't see a 1pi*

[Winga]

Yes, you can't see any pi* orbitals from the figure, but the orbitals should be existed.

As you said the 2 e- are shared by the 4 carbon atoms, so, how they share?

[movies]

Yes, you can't see any pi* orbitals from the figure, but the orbitals should be existed.

The pi* orbitals are shown, they are pi4, pi5, and pi6.  Each one has a corresponding bonding orbital among pi1, pi2, and pi3.

The "sharing" that Mitch refers to is just the energy levels where the electrons are most likely at.  In orbitals like pi3 the adjacent p-orbitals mix together because they are in phase with one another to make a true pi-orbital, which is a double bond.  The sharing really just means that there is essentially no energy involved in an electron moving between the two orbitals.

There is no electron density around those atoms. That's the whole point of a node.

This is why there is why the p-orbitals have a coefficient of zero on those atoms!