Rahul,
Instance dependent method means that the method uses the key of the business object which you are using.
To test this, First go to the test screen of the business object, then click the create instance button on top. Now enter the key of the object.
When you are done with creating the instance you can click the execute button next to the method to test it.
In case of Instance independent method, you do not have to create a instance of the business object (It is like a static method), when you go into the test mode, you will see the instance independent methods listed, just click on it to execute.
