Dim compressor As New XceedStreamingCompressionLib.XceedStreamingCompressionClass() 

compressor.License( "your license key" ) 

compressor.CompressionFormat = New XceedStreamingCompressionLib.XceedBZip2CompressionFormatClass()

Dim bytesRead As Object = Nothing

Try
  Dim compressedData As Object = compressor.ReadFile( "c:\test\file.txt", 0, 0,
                                 XceedStreamingCompressionLib.EXCFileProcessing.cfpCompress, true,
                                 bytesRead )              
Catch except As System.Runtime.InteropServices.COMException
  MessageBox.Show( except.ToString() )
End Try