IOrganizationService in CRM 2011 - HomeRealmUri

Uri organizationUri = new Uri("http://crmservername/orgname/XRMServices/2011/Organization.svc");
var homeRealmUri = null;
ClientCredentials credentials = new ClientCredentials();
// set default credentials for OrganizationService
credentials.Windows.ClientCredential = (NetworkCredential)CredentialCache.DefaultCredentials;
// or
credentials.Windows.ClientCredential = System.Net.CredentialCache.DefaultNetworkCredentials;
OrganizationServiceProxy orgProxy = new OrganizationServiceProxy(organizationUri, homeRealmUri, credentials, null);
IOrganizationService _service = (IOrganizationService)orgProxy;
try
{
    Entity myAccount = new Entity("account");
    myAccount["name"] = "Test Account";
    _service.Create(myAccount);
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}
}


For Early bound:

OrganizationServiceProxy _serviceProxy = new OrganizationServiceProxy(organizationUri, homeRealmUri, credentials, null);
// This statement is required to enable early-bound type support.
 _serviceProxy.ServiceConfiguration.CurrentServiceEndpoint.Behaviors.Add(new ProxyTypesBehavior());