The unit will not generate a Share when I connect a USB drive on the port on the back. Tried two different drives one of which was a Western Digital but the My Cloud unit does nothing.
Did you look at the User Manual, Connecting a USB Hard Drive?
Also make sure the drive is using a supported file system.
When in the NAS UI, you should be able to see the USB button in the upper right corner. If your disk is detected right, you will see it there.