Hello NAV world

I am totally new to NAV. I am beginning by second career. I am hoping to get a job as an Accounts Payable Billing Clerk using Nav. The company I am hoping to work with is still using NAV 4.0 upgrading to 2015 this fall so I am trying to find all the information I can on Nav 4.0 to hit the ground running. (This is a little difficult because it is no longer supported so the supporting documentation isn't on the website.) I am a quick study and very motivated by personal success so I just need to get that first opportunity to prove myself.