While creating or editing a note, you will see a checkbox "Quick Poll" below the text of your note. If you select this checkbox, several other fields appear:

• A list of the possible answer choices for the vote, and "Add", "Edit" and "Remove" buttons;
• The date and time at which the poll will close;
• A checkbox "...or as soon as everyone has voted"
  

You must add at least two, and at most ten, choices.

A poll always has a set closing date. You can edit the closing date either by typing in the date and time fields, or select a date by pressing the "calendar" button to choose from a popup calendar.