When creating a new thread, the poll option should be at the very bottom. Check the box
then click "Submit New Thread" and it should create your thread. You only have the option to edit the poll,
after the thread is created.
You will be re-directed to the new thread page where you will have to input your poll question, the number of poll options, what the options are, and by what time the poll should stop taking votes. Additionally, you can also make it so that you can see who voted for what option (aka public poll) and allow people to vote for more than one thing, if you are so inclined.
example:-
http://www.fiestafan.com/forums/showthread.php?t=5731