Molecule Shapes and Resonance

In class for our second lesson, we talked about the various shapes a molecule can take as well as resonance  To have resonance, it means that a compound had multiple bonds, and when you move one of the bonds it has, it must fit in any given place. This is what it looks like:

https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Carbonate-ion-resonance-2D.png/380px-Carbonate-ion-resonance-2D.png

As shown, the double bond can be moved to any of the three sides of the molecule, and it is still the same; This means it has resonance.
The next thing that we talked about are the selection of shapes that the molecules that we deal with can have. The five primary shapes that our teacher told us we would be working with are: a trigonal planar molecule has three bonded entities to the central atom and the central atom does not have any lone pairs, a tetrahedral molecule which has 4 bonded entities around one central atom, a linear molecule has two bonded entities to the central atom and this does not have a lone pair, a trigonal pyramidal molecule which has three bonded entities and one lone pair of electrons around the central atom, and a bent molecule which has two bonded entities with two lone pairs of electrons around the central atom.
This is what these five look like:

http://cnx.org/contents/d5d1d182-3eb0-419a-bfda-3615e56fafea@1

Here are some more links to help. I found the shapes to be fairly tricky to remember and practice.
http://intro.chem.okstate.edu/1314f00/lecture/chapter10/vsepr.html
https://www.chem.wisc.edu/areas/clc/organic/343/02_resonance_structures_343_ans.pdf