CC2520 is just a Zigbee transceiver, you will need a host microcontroller...
Which microcontroller are you using to communicate with your CC2520?
If you are using a MSP430, Texas Instruments will probably have examples on how to interface a CC2520 with a MSP430, have a look at https://focus.ti.com/docs/prod/folders/print/cc2520.html. There you will find T.I.'s technical documentation related to CC2520.