How to Zip the folder using C#

public static void AddFolderToZip(string sourcePath,string zipFullName)
        {
            DirectoryInfo CurrentFolder = new DirectoryInfo(sourcePath);
            DirectoryInfo RootFolder = CurrentFolder.Parent;
            DirectoryInfo[] SubFolders = RootFolder.GetDirectories(CurrentFolder.Name);
                       
            if (SubFolders.LongLength > 0)
            {
                //Add all subfolders to the zip if any
                for (int i = 0; i < SubFolders.Length; i++)
                {
                    ProcessStartInfo p = new ProcessStartInfo();
                    p.FileName = "7za.exe";
                    if (!(new FileInfo(zipFullName).Exists))
                    {
                        p.Arguments = "a -tzip \"" + zipFullName + "\" \"" + SubFolders[0].FullName + "\" -mx=9";
                    }
                    else
                    {
                        p.Arguments = "u \"" + zipFullName + "\" \"" + SubFolders[i].FullName + "\" -mx=9";
                    }
                    p.WindowStyle = ProcessWindowStyle.Hidden;
                    Process x = Process.Start(p);
                    //x.WaitForExit(500);                   
                    x.WaitForExit();
                }               
            }
        }
/* Calling a Method to zip the file using 7za.exe*/
string SourceFolder= ConfigurationManager.AppSettings.Get("SourceFolder");
string ZipFolderPath = ConfigurationManager.AppSettings.Get("ZipFolderPath");
ZipFolderPath= ZipFolderPath.EndsWith("\\") ? ZipFolderPath : ZipFolderPath + "\\";
ZipFolderPath= ZipFolderPath + "test.zip";
ZipHelper.AddFolderToZip(SourceFolder, ZipFolderPath);