Info about X-architecture

[Timo Juhani Lindfors]

vijay singh <testmrs.evo at gmail.com> writes:
> I would like to know is their any document available which will explain
> about X-architecture.  

Even just http://en.wikipedia.org/wiki/X_Window_System gives a rough overview.

> if i want to add any new X-client then what is the way.

Things like evolution and firefox usually work as X clients on
gnu/linux. You can take a look at them or google for "GTK hello world"
or "QT hello world" to get something simpler.