Which Customs Forms Do I Use? (see this link)

Regardless of value or contents, every Priority Mail International package must bear a completed PS Form 2976-A Customs Declaration and Dispatch Note that is inserted into Plastic Envelope, PS Form 2976-E.

• If you open an account at usps.com, you can complete the form online and print from the USPS generated PDF files. If will fill in your address information each time you use it.
• If you print postage online at usps.com (such as at click-n-ship), forms will be generated too.
• You will also need the clear-plastic envelope (provided free from the Postal Service) to place the five (5) half sheets that you printed into.  Note: The plastic envelope is larger than the heigth and width of a half-sheet piece of paper, with a flap.  Therefore, you package surface area must be large enough to accommodate along with address and stamps and other required markings.  It also adds about 1 - 2 oz. to the weight.
  
• You can get free 2976-E envelopes (i.e. known as forms) at your Post Office, or here: https://shop.usps.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10052&productId=10000267&langId=-1&catalogId=10001

After you open an account at USPS.com, you can print the PS Form 2976-A at this link:

Learn about customs forms (or register) at the USPS website here:

You can get free 2976-E envelopes (i.e. known as a form) at your Post Office, or here: