In each version of Oracle, there's a management tool. I won't mention the name of it here, because the name keeps changing. However, it should be on your menues or in your applications list. You can navigate from database to schema, and within the schema see your tables, views, and program objects. Within tables, you can see columns, triggers, constraints, indeces, and the like. Within program objects, you can see procedures, functions, and packages.
To determine which tables are used in views, you can go to views and display the view definition. To determine which tables and views are used in program objects, you can go to the particular program object, and display its definition.
Sheldon Linker (firstname.lastname@example.org)
Linker Systems, Inc. (www.linker.com)