A poll on what subject? For what purpose?
Do you mean you want to post a poll here on Sitepoint? If so, start a new thread, and scroll down to "Post a Poll" and tick the box. But I believe that not all members have the right to create a poll, and I'm not sure what the criteria are.
Or, do you mean you want to create a poll outside of Sitepoint, that is accessible to anyone in the world? If so, there are several sites that allow you to do that. The best known is SurveyMonkey.