Siva,
Please see WmEDISamples packages provided in the Developer it has xmltoedi and editoxml flow samples,mapping procedures.As a starter for EDI world please go thru the webMethods EDI Module Users Guide,ISDeveloperUserguide for better understanding.
Search this forum for EDI related threads,tons of queries/responses are available.
HTH,
RMG
#edi#Integration-Server-and-ESB#webMethods