In that case, you would replace:
MsgBox StrOut
with code like:
Call UpdateBookmark("bookmark_name", StrOut)
where 'bookmark_name' is the name of the bookmark you want to update, plus add the following sub to the same code module:
Code:
Sub UpdateBookmark(StrBkMk As String, StrTxt As String)
Dim BkMkRng As Range
With ActiveDocument
If .Bookmarks.Exists(StrBkMk) Then
Set BkMkRng = .Bookmarks(StrBkMk).Range
BkMkRng.Text = StrTxt
.Bookmarks.Add StrBkMk, BkMkRng
End If
End With
Set BkMkRng = Nothing
End Sub