Setting usability tasks for participants to test a website

I recently designed a website and I would like to test its' usability against end users.

I am not sure about how I would set tasks, as I have read online not to give any obvious clues.

One task I would like users to undertake, is to vote on a poll. Now this poll is on my homepage - and simply telling the user to vote on the poll is practically countering against the whole purpose of usability testing. This is how I have defined this task (see below), however I do not know if the task is clear and if I have given away too much information.

The task:

You are entitled to a voice and you are able to express your thoughts and views to some of the questions published on this website. How would you go about answering some of these questions?

Firstly, how can I rephrase and improve the above task? Secondly, what are examples of usability issues?

Would appreciate it if someone could modify my task or give me some general advice.