Depends on how you wrote the class.
A normal, non-static class, you have to make an object, then call the methods.
If it's static, you can just call the methods.
You need to include it like any other class with the include directive.
So, you either do like
CheckEmpId myObj = new CheckEmpId();
myObj.myMethodCall();
or, if static, just
CheckEmpId.theMethodName();
Oh, don't forget classpath and all that jazz.
Greetings.