Private Sub btnInputData_Click()
Application.ScreenUpdating = False
Dim wdDoc As Document
Set wdDoc = ActiveDocument
Call UpdateBookmark(wdDoc, "bmSite", Me.txtSite.Value)
Call UpdateBookmark(wdDoc, "bmclient", Me.txtClient.Value)
Call UpdateBookmark(wdDoc, "bmContactNo", Me.txtContactNumber.Value)
Call UpdateBookmark(wdDoc, "bmProjectManager", Me.txtProjectManager.Value)
Call UpdateBookmark(wdDoc, "bmSupervisor", Me.txtSupervisor.Value)
Call UpdateBookmark(wdDoc, "bmProjectNo", Me.txtProjectNumber.Value)
Call UpdateBookmark(wdDoc, "bmStartDate", Me.DTPicker1.Value)
Call UpdateBookmark(wdDoc, "bmEndDate", Me.DTPicker2.Value)
'
'The rest of your code, from 'Print Sections' onwards, goes here
'
wdDoc.Fields.Update
Set wdDoc = Nothing
Application.ScreenUpdating = True
End Sub
'
Sub UpdateBookmark(wdDoc As Document, BmkNm As String, NewTxt As String)
Dim BmkRng As Range
With wdDoc
  If .Bookmarks.Exists(BmkNm) Then
    Set BmkRng = .Bookmarks(BmkNm).Range
    BmkRng.Text = NewTxt
    .Bookmarks.Add BmkNm, BmkRng
  End If
End With
Set BmkRng = Nothing
End Sub