' For complete examples and data files, please go to https://github.com/groupdocs-watermark/GroupDocs.Watermark-for-.NET
Using doc As Document = Document.Load(Utilities.MapSourceFilePath(XlsFilePath))
Dim font As New Font("Calibri", 12)
Dim watermark As New TextWatermark("Test watermark", font)
watermark.HorizontalAlignment = HorizontalAlignment.Right
watermark.VerticalAlignment = VerticalAlignment.Bottom
' Set relative margins. Margin value will be interpreted as a portion of appropriate parent dimension.
' If this type is chosen, margin value must be between 0.0 and 1.0.
watermark.Margins.MarginType = MarginType.RelativeToParentDimensions
watermark.Margins.Right = 0.1
watermark.Margins.Bottom = 0.2
doc.AddWatermark(watermark)
doc.Save()
End Using