I can't supply the missing detail because you seem to forget to add the figure. However, I would just start from scratch in order to provide to you the complete Lewis Structure.
Carbonate ion is CO₃²⁻ in chemical formula. The first thing to do is add up the valence electrons of each individual atoms. Carbon has 4, Oxygen has 6 plus 2 more electrons gained as an anion. So, the total valence electrons is: 4 + 6(3) +2 = 24. So, there must be 24 electrons that surround the molecule. You must distribute these to the atoms by knowing the types of bonds involved. Note that each single bond connecting two atoms in the compound contains two electrons. It is also crucial to always obey the Octet Rule. This rule states that every atom has to be filled with eight electrons in order to be stable.
Thus, the complete Lewis Structure is shown in the picture. All in all there are 16 dots which represent the unshared electrons. Then, two single bonds represents 2 pairs of electrons shared. Same is true for the double bond containing 4 electrons shared. The total is 24 electrons.
