I need primary sources on the opium wars in China.

A google search using the keywords, opium china and "primary sources" will find other sites such as these:

• Voice of the Shuttle: links to sites about the Opium War.
• Digital China: Harvard: The Opium War - this has links to many primary source documents

Hot tip: when searching google, if you put double speech marks " " around your search term, google will search for it as a phrase.  Very handy if you're looking for something in particular and you know the words will be in that order.