I'd like to insure this package.
Small packets require a green customs form only.
Small packet, books only packages require no customs form, but if they ask you to, just use it. Be sure you pay for the insurance and get a little red sticker which says as much on your copy of the form. Packages which are too big or heavy to be a small packet also use the white form. I'd like to change dollars into yen. Most foreign exchange clerks speak rudimentary English.