A lot of work has been done, up to this point. Form fields have been created, files have been selected and a small API has been called to retrieve the cryptographic signature that AWS S3 needs.
What's left, then, is to take the signature, policy and other form fields that are returned from the API, populate the HTML form fields and submit the form!
In this episode, the upload to Amazon S3 is finally complete. You'll see the end result of selecting a file, clicking the submit button and seeing AWS S3 accept the file.