unable to use existing Firefox profile with webdriver

Hi , I am unable to use existing Firefox profile , i have done evrything as you said in your video to use existing firefox profile in module 11
Here is the code that i have written:
package com.tst;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.firefox.FirefoxProfile;
import org.openqa.selenium.firefox.internal.ProfilesIni;

public class Profile {

public static void main(String[] args) {
ProfilesIni profile = new ProfilesIni();
FirefoxProfile myProfile = profile.getProfile("Default");

WebDriver driver = new FirefoxDriver(myProfile);


}

}


Errors i am getting are :
Exception in thread "main" java.lang.IllegalStateException: The path to the driver executable must be set by the webdriver.gecko.driver system property; for more information, see https://github.com/mozilla/geckodriver. The latest version can be downloaded from https://github.com/mozilla/geckodriver/releases
at com.google.common.base.Preconditions.checkState(Preconditions.java:199)
at org.openqa.selenium.remote.service.DriverService.findExecutable(DriverService.java:109)
at org.openqa.selenium.firefox.GeckoDriverService.access$100(GeckoDriverService.java:38)
at org.openqa.selenium.firefox.GeckoDriverService$Builder.findDefaultExecutable(GeckoDriverService.java:91)
at org.openqa.selenium.remote.service.DriverService$Builder.build(DriverService.java:296)
at org.openqa.selenium.firefox.FirefoxDriver.createCommandExecutor(FirefoxDriver.java:245)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:220)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:215)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:211)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:128)
at com.tst.Profile.main(Profile.java:14)