Maybe this will do what you want (You did not give much to go on)

Macro to set the first label on a part sheet of labels for a label type
mailmerge.

Dim MMMDoc As Document

Dim dsource As Document

Dim dtable As Table

Dim i As Long, j As Long

Set MMMDoc = ActiveDocument

With MMMDoc.MailMerge

   If .MainDocumentType = wdMailingLabels Then

       If .State = wdMainAndDataSource Then

           Set dsource = Documents.Open(.DataSource.Name)

           Set dtable = dsource.Tables(1)

           i = InputBox("Enter the number of labels that have already been
used on the sheet.", "Set Starting Label")

           If IsNumeric(i) Then

               With dtable

                   For j = 1 To i

                       .Rows.Add BeforeRow:=.Rows(2)

                   Next j

               End With

           End If

           .Destination = wdSendToNewDocument

           .Execute

       End If

   End If

End With

dsource.Close wdDoNotSaveChanges

Do you mean "how do I print labels in the unused part of a used sheet of
labels" ?

If so, are you printing multiple copies of the same label, or are you
mailmerging to labels? Are you only ever printing labels on a single sheet
at a time?

Peter Jamieson