Private Sub AddToArchive(ByVal zip As Package, _ 
                         ByVal fileToAdd As String)

        'Replace spaces with an underscore (_) 
        Dim uriFileName As String = fileToAdd.Replace(" ", "_")

        'A Uri always starts with a forward slash "/" 
        Dim zipUri As String = String.Concat("/", _ 
                   IO.Path.GetFileName(uriFileName)) 

        Dim partUri As New Uri(zipUri, UriKind.Relative) 
        Dim contentType As String = _
                   Net.Mime.MediaTypeNames.Application.Zip

        'The PackagePart contains the information: 
        ' Where to extract the file when it's extracted (partUri) 
        ' The type of content stream (MIME type):  (contentType) 
        ' The type of compression:  (CompressionOption.Normal)   
        Dim pkgPart As PackagePart = zip.CreatePart(partUri, _
                   contentType, CompressionOption.Normal)

        'Read all of the bytes from the file to add to the zip file 
        Dim bites As Byte() = File.ReadAllBytes(fileToAdd)

        'Compress and write the bytes to the zip file 
        pkgPart.GetStream().Write(bites, 0, bites.Length)

    End Sub