JUnit test failed to launch

I am doing my first JUnit test project but its not working.

I did two methods two test.

my console is giving me message " Failed to launch test" !

How can I solve it ?

package test;

public class Junit {

public String concentrate (String one, String two){ 

    return one + two;

}

public int multiply (int number1, int number2 ){

    return number1*number2;

}



}