How do I shop on the Kindle store through a usb connection?

Is it not even possible? The wifi connection in my house is down right now so Ive been trying to use the usb connection. I plug in the usb but I cant access the kindle itself without ejecting it from the computer (this is what it says on the kindle). I cant figure out how to eject the kindle and therefore have no idea where to go after that. Any help ejecting it would be great too