How to Create an Event for a User Control

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class ctrlCalculator : System.Web.UI.UserControl
{
    public delegate void CalculationInProgress(object sender, OperationEventArgs e);
    public event CalculationInProgress Calculating;

    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnPerformOperation_Click(object sender, EventArgs e)
    {
        this.Calculating(this, new OperationEventArgs(Operation.Addition, Convert.ToDecimal(this.txtValue1.Text) + Convert.ToDecimal(this.txtValue2.Text)));
        this.Calculating(this, new OperationEventArgs(Operation.Subtraction, Convert.ToDecimal(this.txtValue1.Text) - Convert.ToDecimal(this.txtValue2.Text)));
        this.Calculating(this, new OperationEventArgs(Operation.Multiplicaiton, Convert.ToDecimal(this.txtValue1.Text) * Convert.ToDecimal(this.txtValue2.Text)));
        this.Calculating(this, new OperationEventArgs(Operation.Division, Convert.ToDecimal(this.txtValue1.Text) / Convert.ToDecimal(this.txtValue2.Text)));
    }
}