How to Do Parallel Test Execution In Selenium TestNG Example Program?

Parallel Test Execution TestNg Program: How to Do Parallel Test Execution In Selenium TestNG Example Program?

package com.selenium.TestNG;
import org.testng.annotations.Test;
public class ParallelTestExec 
{
   @Test
   public void test1()
   {
      System.out.println("Test1 Executed");
      System.out.println("Test Case One with Thread Id:- "+ Thread.currentThread().getId());
   }
   @Test
   public void test2()
   {
      System.out.println("Test2 Executed");
      System.out.println("Test Case Two with Thread Id:- "+ Thread.currentThread().getId());
   }
}