The structure should look like this:
Work Step by Step
1. Draw the basic changes, the bonds that are formed, the lone pairs that are added, and don't forget to erase the ones that are in the tail of the arrow. 2. Check the formal charges, remembering that, the total sum of the charges in the molecule will not change in resonance, so, if the left structure has +2 as a formal charge, the right structure will have +2 as well.