Ideas for best way to put door on pole barn

[Scott Passman]

I recently acquired a property that has a structurally sound pole barn in the back. Looking to rent it out as storage for additional income, but I need to secure it with doors first so it can be locked.  The height size of the opening is roughly 8.5' x 16'.  Any ideas on the most cost effective ways to either self-install or hire out an installation of this door?  Thoughts on the best materials to use?