This article covers pairing your iPad with the Paypal Here card reader.
Go to the 'Settings' on your iPad, go to Bluetooth and make sure it is turned on.
Press and hold the pairing button on the Card reader. This is located on the front, in the top right hand corner next to the PayPal logo.
In 'Settings -> Bluetooth' on your iPad and you should see the same device name that is specified on the card reader (in this example, Paypal 671).
Click on the device in the list of devices to pair with it.
Now you have paired your PayPal Here Card Reader, you may want to look at Making a Card Payment with PayPal