You don't really have enough information to get specific assistance. I'll give you the generic answer and a couple suggestions, but you'll need to provide more specific information on what your problems are to get anything specific.

Normally, you interrogate controls using the bullseye icon on the interrogation form. If you cannot highlight a specific control (and assuming that the application is a web-based one), you can try using the Select Element option to select specific HTML tags to interrogate. If this doesn't work, then you may need to switch to the Web Controls tab and add the controls from there.

@sasnt   Thanks for your response but I  found issue in my browser setup.

Once I have increase browser Zoom 100% its working fine and able to interrogate popup/alert message.