This example creates a new LetterContent object, reserves an inch of space at the top of the page for a preprinted letterhead, and then runs the Letter Wizard by using the RunLetterWizard method.
Set aLetterContent = New LetterContent
With aLetterContent
.Letterhead = True
.LetterheadLocation = wdLetterTop
.LetterheadSize = InchesToPoints(1)
End With
ActiveDocument.RunLetterWizard _
LetterContent:=aLetterContent, WizardMode:=True