you can search for Ajax libraries that can allow you to use drag-and-drop. Two examples I can name are Scriptaculous and Mootools.
(if you haven't looked at the drag-and-drop example from richfaces, look here: http://livedemo.exadel.com/richfaces-demo/richfaces/dragSupport.jsf; you can also take a look at the source). Good luck!
I am already trying it in rich faces but I have problem in dropping components from one form in to another form (likewise dropping text, label, button.. )in another form.
My suggestion would be to create a sort of demo example in which you try out just a type of component(for example a button). After that works you can add more components. If you create something small first and it works you can be sure that when you add something new to it the problem is with the new part, and this way you don't have to recheck the whole page.
I am able to drop component but how to set them in particular position?
I'd suggest you ask this on the RichFaces forum; they can help more, probably.
post in the richfaces forum to get a faster response.
I am putting it in Richfaces forum!!!