" How does it work?"

It is fairly simple but not exactly what you want to hear; the two products are not capable of accepting data from either one in any direction and, unfortunately, do not communicate with each other in any way, shape, or form.

You need to start the appropriate type of return and then enter everything separately into each program. TurboTax Home & Business can import data from multiple sources (but not TurboTax Business) while TurboTax Business can only import data from QuickBooks.