If you do not know who has written or published the content, or if it is not current, then you should first consider if it is suitable for academic work. The Being Digital activity about evaluating information will help.
You can still format a reference for a web page by using the page title in place of the author and 'no date' for the year. You should be able to work out the publisher by checking links to the homepage or a name in the web address.
Find out more by doing the Referencing websites activity on Being Digital.