Hi Sarah, First of all, you do not use the statement 2 times.
And it should be
Headers, not Header.
And no space between
wdHeaderFooterPrimary
And if you wanna use "headerPic", do not Dim "header_pic"....
the code below should work
Code:
Sub AddImageToHeader()
Dim SrcePath As String, headerPic As InlineShape
SrcePath = "S:\DocBase\Document Templates\Macros\New Macros Nov 2018\Letterhead.jpg"
Set headerPic = ThisDocument.Sections.Item(1).Headers(wdHeaderFooterPrimary).Range.InlineShapes.AddPicture(SrcePath)
With headerPic
.Width = 5.11
.Height = 20.96
End With
End Sub