How to use ClassLoader or Class to programatically load a Class

I have two classes

package pack2;
import java.lang.*;
import java.io.*;
class eg
{
    public void show()
    {
        System.out.println("ClassPath set to this class");
    }
}

this is in C:\NNK\pack2. the fully qualified name is pack2.eg

another program is

import java.io.*;
import java.lang.*;
import java.net.*;
class classload
{
    public static void main(String args[])
    {
        //have to load the eg class here. Dont know what i have done below is right or wrong
        try 
        {
            Class b=Class.forName("pack2.eg");
        }
        catch(ClassNotFoundException e)
        {
            e.printStackTrace();
        }
        try
        {
            eg z=(eg) b.newInstance();
        }
        catch(InstantiationException l)
        {
            l.printStackTrace();
        }
        z.show();
        System.out.println("b.getName()="+b.getName());
    }
}

this program is at C:\NNK I have to load the eg program here. I tried to learn it in Oracle saw other related stack overflow questions of it. Dynamically loading a class in Java But it didn't work i keep getting the error b is Unknown and z is unknown symbol. Also is there a way to use the directory filename(eg: C:\NNK\pack2\eg) to load a class