How to change default web site properties (path) with WMI on IIS 6.0 - C#?

public void StartSite(string serverID)
        {
            try
            {
                string serverName = "W3SVC/" + serverID;
                ManagementObject webSite = new ManagementObject(_scope, new ManagementPath(@"IIsWebServer='" + serverName + "'"), null);
 
                App.StdOut("Starting..." + webSite.Path);
                // Check if the website is stopped or paused
                if ((int)webSite["ServerState"] == 4 || (int)webSite["ServerState"] == 6)
                {
                    webSite.InvokeMethod("Start", null);
                }
            }
            catch (Exception ex)
            {
                App.LogException(ex);
            }   
        }
 
        public void DeleteExistingSites()
        {
            try
            {
                ManagementObjectSearcher searcher = new ManagementObjectSearcher(_scope, new ObjectQuery("SELECT * FROM IIsWebServer"), null);
                
                ManagementObjectCollection webSites = searcher.Get();
                foreach (ManagementObject webSite in webSites)
                {
                    App.StdOut("Deleting... " + webSite.Path);
                    webSite.Delete();
                }
            }
            catch (Exception ex)
            {
                App.LogException(ex);
            }
        }
 
        public void SetAspNetVersion(string frameworkVersion, string IISWeb)
        {
            string frameworkDirectory;
            string directory;
            System.Collections.ArrayList al;
 
            //Execute the following command in the correct .net framework version directory.
            //Aspnet_regiis.exe -s W3SVC/1/ROOT/SampleApp1
            if (frameworkVersion != "v1.1.4322")
            {
                al = new System.Collections.ArrayList();
                directory = System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory();
 
                int dirPos = directory.Remove(directory.Length - 1, 1).LastIndexOf(@"\");
                frameworkDirectory = directory.Remove(dirPos, directory.Length - dirPos);
                frameworkDirectory = frameworkDirectory + @"\" + frameworkVersion + @"\";
 
                if (!Directory.Exists(frameworkDirectory))
                {
                    throw new Exception("Cannot find framework.  Check correct framework is installed");
                }
 
                Process process = new Process();
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.RedirectStandardOutput = true;
                process.StartInfo.RedirectStandardError = true;
                process.StartInfo.FileName = frameworkDirectory + "aspnet_regiis";
                process.StartInfo.Arguments = @"-sn " + String.Format(@"W3SVC/{0}",IISWeb);
                process.Start();
                process.WaitForExit();
            }
        }