How to configure my Xbee RS-485 adapter

I would like to send data from my gateway to my end device through the Xbee RS-485 adapter. The gateway also has a xbee module and it can be programmed to send data to any particular destination. Now, I would like to connect my Digi Xbee RS485 adapter to my xbee network, by configuring PAN ID of the gateway, Network channel of the adapter corresponding to that of the gateway settings.

Can anyone guide me on the above?