What H1B application materials are needed in Shanghai?

Per its website:

To apply for an H or L visa, you must have the following:

• A petition approved by the U.S. Department of Homeland Security (DHS) in the United States. (Question - what petition is this?)
• An approved original I-797 and a certified copy of your I-129. (Question - also a certified copy, like a notarized one by the post office?)
• You may also need a certified copy of the I-129 application material. (Question - also a certified copy, like a notarized one by the post office?)
  
  Thanks a bunch!