hi,I have problem how to use usb between mac and apple II

I just read ur answer,like apple II c or before require a card,but I have no this one, and now I have no pc by my side,only macintosh,does anyone knows what kind of way to connect mac and apple II.I have apple II gs,I know a kind of way is db8 to usb,how to do?can I get .DSK file to save 3.5 disk.then take it to apple 2 extract .dsk.like before answer.apple 2 software how to get it.I just know extract.shk does anyone know this?thx