When you start a new thread, there is an option at the bottom which says "Yes, post a poll with this thread" where you can ask one question with up to 10 different answers.
If you're looking for more than that, you can always create a survey/poll somewhere else, and link to it in your post.
[EDIT]
And the answer to your original question is also answered on the same page, where it lists what options are available to you. Just look at the bottom of any page...
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