Giorgio,
The code snippet you posted for JFBConnect to post is for us to post to a user's wall silently after an action has been done. For example, after a user's registered or logged in. In your case, to add that code, you'd probably want to add it to the following file (I don't know Acepolls, so I'm guessing this from the file you posted):
/components/com_acepolls/controller.php (or acepolls.php) in a function called "vote"
The alternative, and what we currently don't make as easy as 3 lines of code, as in the first case, is to pop-up a Facebook box with a pre-filled message of "I just voted on...". We're actually starting a little bit of work on the code to make this into a line you can add to existing forms, as in your case, so that when a user hits submit, it will prompt them to also post something to their wall. If that's what you want to do, let us know, and we may be able to help you implement something before we get it into a full release. For more information on what I'm talking about, see the "Dialogs" section (about 1/2-2/3's the way down):
developers.facebook.com/docs/reference/javascript/
Let us know if this helps, and good luck!