If Settings > Bluetooth is already showing the Belkin keyboard, then it is already paired. All you should need to do is make sure the keyboard is on, then tap the entry on the iPad. It should shortly say Connected.
If it does not, change the batteries, in case they are low.
Also, make sure the keyboard is not currently paired with any other computer or device. If it is, make sure that device/computer is off, or un-pair the keyboard from it.
Good luck.