Assume you have a base class and another class derived from it. You have events defined in base class so you wish to use them in the derived class.

    class a
    {
        public delegate void Amanindelegate();
        public event Amanindelegate Amanin;
    }

    class b:a
    {
        public void hey0()
        {
            Amanin();
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            b b1=new b();
            b1.Amanin+=new a.Amanindelegate(b1_Amanin);
            b1.hey0();
        }
        static void b1_Amanin()
        {
            Console.WriteLine("aboovv");
        }
    }

Here you have the mentioned error in hey0 method line Amanin();
The best practice is as follows.

    class a
    {
        public delegate void Amanindelegate();
        public virtual event Amanindelegate Amanin;
    }

    class b:a
    {
        public override event a.Amanindelegate Amanin;
        public void hey0()
        {
            Amanin();
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            b b1=new b();
            b1.Amanin+=new a.Amanindelegate(b1_Amanin);
            b1.hey0();
        }
        static void b1_Amanin()
        {
            Console.WriteLine("aboovv");
        }
    }