Model importing from 3d max to unity

Hi, I created a football field with goal post in 3d max, every thing works fine except the goal post which i created with lines in 3d max when i import it to unity the goal post which was created by using lines doesn't appear in unity, any one know how to fix it or a link from where i get knowledge about it and how to import 3d max model/ object which are created by shapes in 3d max into unity.