VBA Code to create hover-over message:

Hello All,
I'm trying to figure out how I can build some VBA code that will automatically add hover-over to specific text in a specific column. For example, for every cell in column C, if the number "20" exists, add a hover-message (pop-up box? Not sure what it's called) that would say "California", every time number "30" exists add a hover-message that says "New York", etc.

If someone can just point me to the framework for this I can probably figure out how to iron out the details.

Thanks a ton!