Agreed. RML can be edited in any text editor.

Thank you very much Brett and Ray for answering my question.But still i need small help regarding RML reporting......Brett Can u further elaborate or can u give me some examples from where i can start making small reports directly from RML without converting SXW to RML?

The best way to start learning (IMO) is to start making small tweaks to existing reports and watching how they change, just make a backup of the original RML file first. Change font sizes and spacing around, add another field from the source object in somewhere, that sort of stuff. Once you feel comfortable making little tweaks to existing reports, making your own from scratch won't be as daunting. I can't help much more than that though, at some point you have to just sit down and grind away at it until it starts making sense.