Mark,
The answer comes down to what extension are you using to "Vote"? Are you using Joomla Content's "Vote" feature that is part of it's articles, or something else?
If you are using an extension that we already have Open Graph Action support for (like Joomla Content for the Voting feature), then you wouldn't need any code.
In all cases, you will need to add the "vote" action in your Facebook Developer Area as well as the "object" of whatever is being voted on. Then, just plug those values into the Open Graph area of JFBConnect.
So, let us know how you plan on the voting to work: Joomla's Article's Voting, another extension's "voting" feature, or something you want to code on your own, and we'll gladly help answer more specifically.
Thanks,
Alex