Is it possible to use Dreamweaver to work on Ajax?
I got Ajax plugin using extension manager but dont know how to use it.

AJAX being a technology comprising javascript (which can be implemented within DW) and XML (technically, u can use php, jsp or even html here) can be used anywhere.

You don't need any extension per se. If you know how to write javascript, can parse an xml document/write some pretty nifty backend code using php, jsp, etc, u r good to go. I wd assume an extension is for libraries of code which someone else has created.

I hope this helps.

well one thing about ajax developers now is that many of them are creating their own styles just for the aim of making ajax simple for novices, ever heard of backbase, well i use their apps pretty well and they have an ajax/dreamweaver extention you can install, what it does is to help you with the dreamweaver intellisence attribiute. so when you create backbase tags it quickly gives you options to make you ajax{backbase version} work,

and i got some other extensions from MXCOLLECTIONS too

MxKollections is fine