exception at runtime

while i executing this source code:-
import java.sql.*;

public class MysqlConnect
{
public static void main(String args[])
{
System.out.println("MySQL Connect Example.");
Connection con = null;
String url = "jdbc:mysql://localhost:3306/";
String dbName = "bank";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "1234";
try {
Class.forName(driver).newInstance();
con = DriverManager.getConnection(url+dbName,userName,password);
System.out.println("Connected to the database");
con.close();
System.out.println("Disconnected from database");
}
catch (Exception e)
{
e.printStackTrace();
}
}
}


i got an exception that exception in
thread main java.lang.noclassdeffounderror :class_name. how can i remove this exception. i am executing my prgm on command prompt in window 7. is there is problem in setting the classpath then give me step to step procedure to correct this problem.i am using mysql-essential-5.0.41-win32_1. pls help
thanks in advance