Hey Maryanne, I've only been playing with it for a little and didn't actually print the label - the package was already sent so I didn't another one - but I went in through the "Make an International Shipping Label" option and it gave me the choice to make it first class parcel mail. I then clicked "proceed without paying" to preview it and the print preview looked correct to me, both the customs form and the shipping label on the screen, so I assume I could have paid and had it printed if I'd wanted to.
This is the link I got it from:
https://www.usps.com/business/click-n-ship-for-business.htm.Val, doesn't stamps.com require a monthly fee? At the moment, my business isn't doing well enough for me to afford a service I'm not sure I'll use often.