On the USB,
Most cases come with wires you plug right onto the Motherboard.
The wires and the board should be labeled.
With all due respect, I think you need a little more guidance on building this thing. I would reccommend getting a book on the subject and brushing up. When I was starting out, a book that helped me (and I still sometimes refer to) was
Upgrading and Repairing PCs
by Scott Mueller, Craig Zacker
Here is a link: