How to set up word document header in delphi5?

I have a set code for the current page

var

mmmm,nnn,aaa:OleVariant;

Begin

mmmm:=wdLine;

nnn:=1;

aaa:=wdFieldPage;

WordApp.ActiveWindow.ActivePane.View.SeekView :=wdSeekCurrentPageHeader;

WordApp.Selection.Move(mm,nnn);

WordApp.Selection.ParagraphFormat.Alignment := wdAlignParagraphCenter;

WordApp.Selection.InsertAfter('Part');

mmmm:=wdCharacter;

WordApp.Selection.Move(mm,nnn);

WordApp.Selection.Fields.Add(WordApp.Selection.Range,aaa,mmm,nnn);

aaa:=wdFieldNumPages;

WordApp.Selection.InsertAfter('Page/Chapter');

WordApp.Selection.Move(mm,nnn);

WordApp.Selection.Fields.Add(WordApp.Selection.Range,aaa,mmm,nnn);

WordApp.Selection.InsertAfter('Page');

WordApp.ActiveWindow.ActivePane.View.SeekView := wdSeekMainDocument;

end;

But you can only modify the first page. How to modify the header of the subsequent page?