XceedStreamingCompressionLib.XceedStreamingCompression compressor =
                new XceedStreamingCompressionLib.XceedStreamingCompressionClass(); 

compressor.License( @"Your license key" ); 

compressor.CompressionFormat =
                new XceedStreamingCompressionLib.XceedBZip2CompressionFormatClass();      

object sourceData = "This is the data to compress compress compress";      
try
{
  object compressedData = compressor.Compress( ref sourceData, true );
}
catch( System.Runtime.InteropServices.COMException except )
{
  MessageBox.Show( except.ToString() );
}

XceedStreamingCompressionLib.XceedStreamingCompression compressor = 
                 new XceedStreamingCompressionLib.XceedStreamingCompressionClass(); 

compressor.License( @"Your license key" ); 

compressor.CompressionFormat =
                 new XceedStreamingCompressionLib.XceedBZip2CompressionFormatClass();

try
{ 
  object decompressedData = compressor.Decompress( ref compressedData, true );        

  MessageBox.Show( System.Text.Encoding.Unicode.GetString( ( byte[] )decompressedData ) );
}
catch( System.Runtime.InteropServices.COMException except )
{
  MessageBox.Show( except.ToString() );
}