How to Use dynamic method Delegate to invoke a method

 public class TestClass
    {
        public TestClass()
        {

        }

        void firstmethod(int i,int j,string k)
        {
            Console.WriteLine("first method");
        }
        void firstmethod(int i, int j)
        {
            Console.WriteLine("first method without k");
        }
    }

Using dynamic method via delegate(which is faster found by reading online) How can i call a method in the TestClass?