Debug after Hyperlink is clicked

Dear Experts,

I need to know where the code is written when 'Approve' or 'Reject is clicked.

There is a FM which is being called in a program when the user submits the form.

The FM has the following piece of code:

CONCATENATE '<a href=link' number '&level=L1'

        '&userid=' ls_approver-level1 '>Approve</a>' into ls_message-line.

      CLEAR ls_message_temp.

      APPEND ls_message TO it_message.

CONCATENATE '<a href=link' number

       '&userid=' ls_approver-level1  '&level=L1' '>Reject</a>' into

       ls_message-line.

How do I find out where the code is written when we approve of reject.

How is that link is created?

Where it is updating the table after clicking Approve or Reject?

Regards

Mani