IIS Binding from c#

CreateSite.cs

// Get IIS reference (create a reference to Microsoft.Web.Administration)
                ServerManager serverManager = new ServerManager();

                // Create new AppPool or use existing
                ApplicationPool appPool = serverManager.ApplicationPools.FirstOrDefault(x => x.Name == appPoolName);

                if (appPool == null)
                    appPool = serverManager.ApplicationPools.Add(appPoolName);

                // Umbraco is .NET 4.0
                appPool.ManagedRuntimeVersion = "v4.0";

                // Add site and configure
                string physicalPath = System.IO.Path.Combine(siteLocation, UmbracoGenerator.Code.Constants.UmbracoRuntimeRelativePath);
                serverManager.Sites.Add(appPoolName, physicalPath, 80);

                serverManager.Sites[StartArguments.Name].ApplicationDefaults.ApplicationPoolName = appPoolName;
                serverManager.Sites[StartArguments.Name].Bindings.Clear();
                serverManager.Sites[StartArguments.Name].Bindings.Add("*:80:" + hostName, "http");
                serverManager.Sites[StartArguments.Name].ServerAutoStart = true;

                // Commit
                serverManager.CommitChanges();

I need to assign a site created a specific user credentials, as I do it??