Carla, if you already signed up for Google AdSense, you don't have to do anything else. HubPages will automatically send you your payment on the 28th of the month following the month in which you reach the payout amount ($50.00).
Example, if you reach $50.00 in April, you will receive payment on the 28th of May.
Just in case you haven't signed up, here is the link explaining how to do it. http://hubpages.com/learningcenter/signup-AdSense.