Zigbees can be interfaced with controllers using thier USART section i.e. Tx and Rx pins.
If your are looking for some information on how to establish connection between two or more Zigbees, then you should try using X-CTU. It is a computer software specially made to configure Zigbees. You can get this on DIGI's website; DIGI is the company who created Zigbee protocol.