Whenever you post a new thread, you have the area where you enter the post, then just below it, buttons for submitting the post or previewing it. Below those buttons is a section called "Additional Options." Most of the time there is no reason to use any of these, but if you want to include a poll with your thread, then you'll find that option at the end of that section. I believe it is a checkbox and, if I remember correctly, if you check it and then submit your post, you will then be given options for the poll, etc. before submitting your final post/poll.