Nissan Almera S,2002. How to add CD changer to it?

I just bought a Nissan Almera 1.5 S, Reg-2002. It has an in-built Cassette & Radio with steering wheel controls.
The Stereo face reads RDS EON CD Changer Control, CT 020.

I was wondering if I can add a CD changer with this stereo and if it might be having CD playing capabilities in built?

Can anyone please shed light on this? I'm loving this car and want it to be perfect and so any help in bringing in a CD player/changer will be appreciated.

Thanks, Terry