Web portal programming for Microsoft Dynamics CRM

First, by creating an ASP.NET project (WebForms or MVC 3), add the following links:

• Microsoft.crm.sdk.proxy.
• Microsoft.xrm.sdk.
• System.Runtime Serialization
• System.ServiceModel.

In your code to create the class, then add the following code:

private IOrganizationService GetCrmService(string userName, string password, string domain, Uri serviceUri)
{
    OrganizationServiceProxy _serviceProxy;

    ClientCredentials credentials = new ClientCredentials();
    credentials.Windows.ClientCredential = new System.Net.NetworkCredential(userName, password, domain);
    //credentials.UserName.UserName = userName;  // uncomment in case you want to impersonate
    //credentials.UserName.Password = password;
    ClientCredentials deviceCredentials = new ClientCredentials();

    using (_serviceProxy = new OrganizationServiceProxy(serviceUri,
                                                        null,
                                                        credentials,
                                                        deviceCredentials))
    {
        _serviceProxy.ServiceConfiguration.CurrentServiceEndpoint.Behaviors.Add(new ProxyTypesBehavior());
        return (IOrganizationService)_serviceProxy;
    }
}

If you want to get multiple entries:

string fetch = @"My Fetch goes here";
EntityCollection records = getCrmService().RetrieveMultiple(new FetchExpression(fetch));

I highly recommend downloading the SDK or checking out this. You will find many examples and walkthroughs to help you build good portals.