public class Foo
{
    public delegate void MyEvent(object sender, object param);
    event MyEvent OnMyEvent;

    public Foo()
    {
        this.OnMyEvent += new MyEvent(Foo_OnMyEvent);
    }

    void Foo_OnMyEvent(object sender, object param)
    {
        if (this.OnMyEvent != null)
        {
            //do something
        }
    }



    void RaiseEvent()
    {
        object param = new object();
        this.OnMyEvent(this,param);
    }
}