Train Pull

How do I train to be able to do pull ups?

When I was younger I had a problem with my knee that put me out of anything physical but watching TV on my coach. Since then I’ve been struggling to keep up with my gym class and such. I was thinking about joining the US marines but they require 2 pull ups for a physical training test. As it stands I can’t do any. What is the best way to train for doing pull ups?

If you have access to a lat machine, you can workout with that and work your way up to it.

World Strongman Entertainment Train Pull 76220 lbs.