I remember how it all started for me. A former driver told me what to do, although these days it probably wouldn't work. He said go to the building but not too early as everyone would be scrambling to get the trucks out the door. dress nice but don't over-do it. Walk up to someone who looks like they might be somewhat in charge, look him in the eye and say " I am interested in working here".
I did as instructed and the supervisor told me they weren't hiring. As I was leaving he called me back and gave me a name and phone number. The rest is as they say, history. Hired on as a jumper (you can tell I go back a ways) that xmas and then they hired me on the re-load. Six years later with my teaching degree and a couple years substitute teaching under my belt, I bid on a driver job to check it out, thinking if it was torture, I would leave and go teach. Needless to say I discovered I could do it and even enjoyed it.
Good luck.