Note this videos have been created with Apex 4 however the same principles and steps apply to Apex 5.

Video tutorial, Oracle APEX report with images, part 1

Video tutorial, Oracle APEX report with images, part 2

Video tutorial, Oracle APEX report with images, part 3

Video tutorial, Oracle APEX report for sales orders, part 1

Video tutorial, Oracle APEX report for sales orders, part 2

Video tutorial, Oracle APEX report for sales orders, part 3