hi Teja,
you can bind the "firstDayOfWeek" attribute of the DateNavigator to a context attribute (SimpleType = com.sap.ide.webdynpro.uielementdefinitions DayOfWeek). in your wdDoInit() method you can set this value. Example - the binded attribute is "dayOfWeek":
wdContext.currentContextElement().setDayOfWeek(WDDayOfWeek.SATURDAY);
which would result in
regards,
christian