I am new to HubSpot, please help. I work for a B2C company selling ebooks. In my sales application, whenever a sale is made, I would like to pass the email, book name, auther name and sell date back to hubspot, and mark it against the contact. Can you please advise how to accomplish it. One way I could think of could be behind the scene form submission, but that is too open to the world. Is there any API integration available?