Creation of simple plugin in crm

using System;
using System.ServiceModel;

// Microsoft Dynamics CRM namespace(s)
using Microsoft.Xrm.Sdk;

namespace Microsoft.Crm.Sdk.Samples
{
  public class FollowupPlugin: IPlugin
 {
  /// <summary>
        /// A plug-in that creates a follow-up task activity when a new account is created.
  /// </summary>
        /// <remarks>Register this plug-in on the Create message, account entity,
        /// and asynchronous mode.
        /// </remarks>
        public void Execute(IServiceProvider serviceProvider)
  {
            //Extract the tracing service for use in debugging sandboxed plug-ins.
            ITracingService tracingService =
                (ITracingService)serviceProvider.GetService(typeof(ITracingService));

            // Obtain the execution context from the service provider.
            IPluginExecutionContext context = (IPluginExecutionContext)
                serviceProvider.GetService(typeof(IPluginExecutionContext));

            // The InputParameters collection contains all the data passed in the message request.
            if (context.InputParameters.Contains("Target") &&
                context.InputParameters["Target"] is Entity)
            {
                // Obtain the target entity from the input parameters.
                Entity entity = (Entity)context.InputParameters["Target"];

                // Verify that the target entity represents an account.
                // If not, this plug-in was not registered correctly.
                if (entity.LogicalName != "account")
                    return;

                try
                {
                    // Create a task activity to follow up with the account customer in 7 days. 
                    Entity followup = new Entity("task");

                    followup["subject"] = "Send e-mail to the new customer.";
                    followup["description"] =
                        "Follow up with the customer. Check if there are any new issues that need resolution.";
                    followup["scheduledstart"] = DateTime.Now.AddDays(7);
                    followup["scheduledend"] = DateTime.Now.AddDays(7);
                    followup["category"] = context.PrimaryEntityName;

                    // Refer to the account in the task activity.
                    if (context.OutputParameters.Contains("id"))
                    {
                        Guid regardingobjectid = new Guid(context.OutputParameters["id"].T

String());
                        string regardingobjectidType = "account";

                        followup["regardingobjectid"] =
                        new EntityReference(regardingobjectidType, regardingobjectid);
                    }

                    // Obtain the organization service reference.
                    IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
                    IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);

                    // Create the task in Microsoft Dynamics CRM.
                    tracingService.Trace("FollowupPlugin: Creating the task activity.");
                    service.Create(followup);
                }
                catch (FaultException<OrganizationServiceFault> ex)
                {
                    throw new InvalidPluginExecutionException("An error occurred in the FollupupPlugin plug-in.", ex);
                }

                catch (Exception ex)
                {
                    tracingService.Trace("FollowupPlugin: {0}", ex.ToString());
                    throw;
                }
            }
        }
    }
}