Programmatically create a web site in IIS using C# and set port number

If you're using IIS 7, there is a new managed API called Microsoft.Web.Administration

An example from the above blog post:

ServerManager iisManager = new ServerManager();
iisManager.Sites.Add("NewSite", "http", "*:8080:", "d:\\MySite");
iisManager.CommitChanges(); 

If you're using IIS 6 and want to do this, it's more complex unfortunately.

You will have to create a web service on every server, a web service that handles the creation of a website because direct user impersonation over the network won't work properly (If I recall this correctly).

You will have to use Interop Services and do something similar to this (This example uses two objects, server and site, which are instances of custom classes that store a server's and site's configuration):

string metabasePath = "IIS://" + server.ComputerName + "/W3SVC";
DirectoryEntry w3svc = new DirectoryEntry(metabasePath, server.Username, server.Password);

string serverBindings = ":80:" + site.HostName;
string homeDirectory = server.WWWRootPath + "\\" + site.FolderName;


object[] newSite = new object[] { site.Name, new object[] { serverBindings }, homeDirectory };

object websiteId = (object)w3svc.Invoke("CreateNewSite", newSite);

// Returns the Website ID from the Metabase
int id = (int)websiteId;

See more here

Heres the solution.
Blog article : How to add new website in IIS 7

On Button click :

try
 {
  ServerManager serverMgr = new ServerManager();
  string strWebsitename = txtwebsitename.Text; // abc
  string strApplicationPool = "DefaultAppPool";  // set your deafultpool :4.0 in IIS
  string strhostname = txthostname.Text; //abc.com
  string stripaddress = txtipaddress.Text;// ip address
  string bindinginfo = stripaddress + ":80:" + strhostname;

  //check if website name already exists in IIS
    Boolean bWebsite = IsWebsiteExists(strWebsitename);
    if (!bWebsite)
     {
        Site mySite = serverMgr.Sites.Add(strWebsitename.ToString(), "http", bindinginfo, "C:\\inetpub\\wwwroot\\yourWebsite");
        mySite.ApplicationDefaults.ApplicationPoolName = strApplicationPool;
        mySite.TraceFailedRequestsLogging.Enabled = true;
        mySite.TraceFailedRequestsLogging.Directory = "C:\\inetpub\\customfolder\\site";
        serverMgr.CommitChanges();
        lblmsg.Text = "New website  " + strWebsitename + " added sucessfully";
     }
     else
     {
        lblmsg.Text = "Name should be unique, " + strWebsitename + "  is already exists. ";
     }
   }
  catch (Exception ae)
  {
      Response.Redirect(ae.Message);
   }

---

Looping over sites whether name already exists

    public bool IsWebsiteExists(string strWebsitename)
    {
        Boolean flagset = false;
        SiteCollection sitecollection = serverMgr.Sites;
        foreach (Site site in sitecollection)
        {
            if (site.Name == strWebsitename.ToString())
            {
                flagset = true;
                break;
            }
            else
            {
                flagset = false;
            }
        }
        return flagset;
    }

Try the following Code to Know the unUsed PortNo

        DirectoryEntry root = new DirectoryEntry("IIS://localhost/W3SVC");

        // Find unused ID PortNo for new web site
        bool found_valid_port_no = false;
        int random_port_no = 1;

        do
        {
            bool regenerate_port_no = false;
            System.Random random_generator = new Random();
            random_port_no = random_generator.Next(9000,15000);

            foreach (DirectoryEntry e in root.Children)
            {
                if (e.SchemaClassName == "IIsWebServer")
                {

                    int site_id = Convert.ToInt32(e.Name);
                    //For each detected ID find the port Number 

                     DirectoryEntry vRoot = new DirectoryEntry("IIS://localhost/W3SVC/" + site_id);
                     PropertyValueCollection pvcServerBindings = vRoot.Properties["serverbindings"];
                     String bindings = pvcServerBindings.Value.ToString().Replace(":", "");
                     int port_no = Convert.ToInt32(bindings);

                     if (port_no == random_port_no)
                    {
                        regenerate_port_no = true;
                        break;
                    }
                }
            }

            found_valid_port_no = !regenerate_port_no;
        } while (!found_valid_port_no);

        int newportId = random_port_no;