How do I link up this device to a PC?

There is a cover under the keyboard in which are located the battery and the USB, just put it in the computer and you’re ready to go, if your device doesn’t come with USB then it is useless.

You can this unboxing video on Youtube.

It supports Bluetooth 2.0. The USB that Hamdi is referring to is a USB dongle that can be stored within the keyboard's bottom compartment that also houses the Sync button. If your PC has Bluetooth already then you likely don't need use of the dongle.