The Letterhead section includes all the fields you will need to control how the PDF will format. It may make sense to put the street address in the "Location" field, and the "New York, NY 10003" entry in the "Street address" field just because of the order they show up on the PDF. Experiment until you like the output. In the US if you're a C-Corp you'll fill out Company tax number, but leave personal tax number blank, and vice-versa if you're a sole proprietorship. Other countries regulations are different of course, so take that into consideration. The footer line can be left blank, or filled in as appropriate for your needs, as can the logo file.