How to run the testcases parallel using tesNG.

How to run the test cases parallel using testing.I tried to run the below code in testing for parallel it is not running parallel.
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TestNG.xml
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<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="My first suite" parallel="tests" thread-count="2">


<test name="ParellelTest TestNG">
<classes>
<class name="ParellelTestTestNG" ></class>
</classes>
</test>

<test name="ParellelTest TestNG1">
<classes>
<class name="ParellelTestTestNG2" ></class>
</classes>
</test>

</suite>
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ParellelTestTestNG.java
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import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.Test;

public class ParellelTestTestNG {

@Test
public void openbrowser(){
System.out.println("Opening the browser");
WebDriver driver=new FirefoxDriver();
driver.get("http://flipkart.com");
}


}
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ParellelTestTestNG2.java
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import org.openqa.selenium.WebDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;
import org.testng.annotations.Test;

public class ParellelTestTestNG2 {


@Test
public void Openbrowser_withurl(){
System.setProperty("webdriver.ie.driver", "D:\\Selenium softwares\\IEDriverServer.exe");
WebDriver driver=new InternetExplorerDriver();
driver.get("http://google.com");
}

}