If you mean a poll at the top of the page then this is how: When creating a thread you will notice the poll option below the main text field. Fill out the info given with the desired answers and if you need to add more answers simply do so by clicking the button below the last possible answer. Select the various options below for multiple choices/public viewing/etc and when you hit "Create Thread" it will appear at the top
Well, I'm not totally sure if there's an official way to do it, so there may be an easier way to do it than what I'm suggesting now. What'd I do is save the voting image onto your computer and then upload it on imgur.com. One you get the BBC code from imgur (assuming you know how to do this, just comment if you don't) put it into your post and make the BBC code into a hyperlink. And... You're done! That's all it should take, hope this helps! Edit: After looking at the comment above mine (which was made while I was posting so I didn't see it)... I think I misread your question Meh, whatever, reference for anyone who needs it lol.