How to setting ip public on OpenFire

I have installed openfire on windows 7 and users chat using spark and users can chat each others ( at office with same ip class )

Openfire server ip : 192.168.5.21 and users ip : 192.168.5.xxx ( domain : openfire-pc )

But how to setting, others ( outside of office / anywhere ) can chat with this users ( other users connect through internet )

Please help…

Do you have at least basic understanding about DNS, SVR records, Routers, Port Forwarding, Firewalls, Internet Domains? If not, this will be almost impossible task and nobody will be able to help you on the forums. You are better hiring some good network administrator then.