Add the Referece for the project - ionic.utils.zip.dll
Add the Namespace using Ionic.Utils.Zip;

String SourLocation = String.Empty;
String DestLocation = String.Empty;
    
protected void Page_Load(object sender, EventArgs e)
{
    try
    {
       SourLocation = ConfigurationManager.AppSettings["SourceLocation"].ToString();
       DestLocation = ConfigurationManager.AppSettings["TargetLocation"].ToString();
    }
    catch (Exception ex)            
    { }
}

protected void btnCreate_Click(object sender, EventArgs e)
{
    ZipFile oSourceZip = null;        
    try
    {
        oSourceZip = new ZipFile(ConfigurationManager.AppSettings["SourceZip"].ToString());            

        if (Directory.Exists(SourLocation))
        {                
            if (Directory.GetDirectories(SourLocation).Length > 0)
            {
                foreach (String sDirectory in Directory.GetDirectories(SourLocation))
                {
                    oSourceZip.AddDirectory(sDirectory, sDirectory.Substring(sDirectory.LastIndexOf("\\") + 1));
                }
            }
            if (Directory.GetFiles(SourLocation).Length > 0)
            {
                foreach (String sfileName in Directory.GetFiles(SourLocation))
                {   
                    oSourceZip.AddFile(sfileName, "");
                }
            }
            oSourceZip.Save();
        }
    }
    catch (Exception ex){ }
}