OK, first your hit the "New Thread" button and put in the title and text. Then, scroll further down the page to the Additional Options > Post a Poll. Check the "Yes, post a poll with this thread" checkbox and enter the number of options you wish to have. Then hit "Submit". The next screen will allow you to fill in the poll questions.
Note: the Additional Options menu is collapsible. If you don't see any options under the Additional Options Toolbar click the little arrows over to the right of the toolbar to open up the menu.