You need to handle the ZipFile.AddProgress and ZipFile.SaveProgress events. Something like this: (check the documentation links for details and code samples)
using (ZipFile zip = new ZipFile())
{
zip.AddProgress += (s, e) => {
// worker.ReportProgress(percentComplete);
};
zip.SaveProgress += (s, e) => {
// worker.ReportProgress(percentComplete);
};
zip.StatusMessageTextWriter = System.Console.Out;
zip.AddFile(@"c:\somefile.txt", "/");
zip.AddDirectory(@"c:\somedir\", "/dir/");
zip.Save(@"c:\myzip.zip");
}