When you're in the thread, on the top right corner of the page (not so high though), you should see "thread tools". Click that, then click on "add a poll to this thread".
Now fill the following :
Poll question : here you put the question you want to ask in the poll.
Number of poll options : Depends on how much answers you want people to vote on, then directly click on "update options".
Option 1... Option 2... etc... : The answers you want people to vote on, each option is one answer.
The rest is quite easy to figure out ;)
And there is no embarrassment in asking a question you know.