Finding the tables, function modules, views & structures used by SAP in a particular transaction are very vital for an ABAP/BAPI developer. There are different ways of finding this information. Below is the best & easiest way I have experienced. Apart from the information mentioned above there is also other information which could come quite handy. I bet you would be amazed to see the information you get.
Goto Transaction "SE38" and key in the program name for which you want to see the underlying tables, function modules, view & structures. Press "SHIFT+F4". 'Environment Analysis' pop-up-window opens. Check the required information and press "ENTER" (By default all the check boxes are checked). If you think it would take longer time to execute this process in foregroud, you have the option to executed in background and this option is seen on the pop-up-window.