I'm not positive if it's an option for you but in the top right corner of your post, there should be a Thread Tools dropdown that contains "Add a Poll to this Thread." After that it's simply asking the question, figuring out how many options you need for the answers and typing in said answers.
The Poll timeout is optional. If it's left at zero, the poll will never close. If you put anything other than that in, that's how many days the poll will be left open. Obviously if you make it too short, no one will have time to vote, so make sure if you're planning on having the poll end, you give it at least a week.
The last two options (Multiple answers and Make votes public) are dependent on the intention of the poll so those options are up to you.
If you have any further questions, feel free to ask.