How to add or create instant messaging in website?

hello friend

i think you need to buy this book

Instant Messaging in Java
The Jabber Protocols
By Iain Shigeoka

This book focuses on the open source Jabber XML-based IM protocols (www.jabber.org) to create Java IM software. These open protocols allows your IM software to seamlessly communicate with the large number of other Jabber clients and servers available including commercial Jabber systems like the one that powers Disney's go.com IM.