For starters a good book on Access is a must! Make sure it's at least two inches thick (not a joke). They can be found cheaply on Amazon.com.
To view the code, first of all open the report in design view. Click on the Events tab and see if there are any entries in the fields shown, especially the OnLoad event. If so, double click on the ellipsis (...) to the right of the field to view the code associated with that event.
You can also open the VBA editor window by pressing Alt+F11 from the main database window. Doing it this way would require you to navigate to the report's code module manually by using the tree view on the left of the VBA editor window.
The answer to your other questions can be found in the book... I'm not trying to put you down, just want you to realize that providing a basic understanding of how databases, and especially Access works is beyond the scope of this forum. I want to encourage your learning process, and I applaud your desire to learn! You can browse our
Howtos section, especially
Normalisation and Table structures also to get a better understanding of how relationships between tables work.
Kind regards,
Scott