To get the database table: From the application menu, go to Help/Record History. This will tell you which database table/view the form uses for storing data. The object listed will usually be a view. You can look up the view definition from DBA_VIEWS to get the underlying table. Some forms will tell you that record history is not available. At that point, enlist the help of an application developer who can look at the form definition to get you the information.
To get the column name from the form: Place your cursor in the field you want from the application menu: Help/Diagnostics/Examine. (It may prompt you for a password; use the APPS password.) This will tell you the forms block name and field name.
Hope this helps,