Hi Mageshwaran,
you could also implement it by using the "Style Group 1".
var paraStyle = app.documents[0].paragraphStyleGroups.itemByName( "Style Group 1" ).
paragraphStyles.itemByName( "find this style" );
app.findTextPreferences.appliedParagraphStyle = paraStyle;
If you have to search through all your paragraph styles, because it's unknown if the style is in a style group, then search the document's allParagraphStyles array like Mark suggested. But note, that there could be more than one style with the same name in a different style group.
That brings me to another thing. If you already know one single text where the paragraph style is applied to or perhaps the user has a selection of that text, work with that text or that selection:
app.findTextPreferences.appliedParagraphStyle =
app.selection[0].appliedParagraphStyle;
Regards,
Uwe Laubender
( ACP )