We'll make you a small guide for it

1. Start the AGI Studio.
2. Open the game you want to edit in the Studio.
3. Go with your mouse to the box where a whole list of resources is named (like view.000 view.001 view.002)
4. From the roll-down menu on top of that list, choose 'Logic'
5. Double-click on a logic. It'll automatically open up.
Here're some tips to find the logic you're looking for. First do the thing from above, but instead of picking 'Logic', choose 'Picture'. Browse through the list in the box and look for the pic of the screen you wish to edit in. Then open the logic with the same number as the pic.
Hope this helps.