Jack Dawson (Leonardo DiCaprio)’s Timeline and Summary

Jack's a poor artist bumming around with a friend when he unexpectedly wins tickets in a poker game to travel on the Titanic.
Early in the journey, he spots Rose from a distance and is clearly smitten. However, as Tommy Ryan points out, it's unlikely that he will find an opportunity to hang out with her (Tommy puts it more colorfully).
However, their paths do cross when Jack finds her contemplating suicide off the back of the boat. He convinces her not to jump, and they strike up a friendship.
Rose's family members do their best to quash the young couple's relationship, but it doesn't work. They go dancing down below the deck, make out (and more) in cars, and engage in a nude drawing session in Rose's rooms.
Unfortunately, their bliss is cut short after Titanic hits an iceberg, and it becomes clear that she will sink. However, Rose and Jack stick together through multiple obstacles, and they go down together with the ship.
Unfortunately, Jack doesn't survive too long in the freezing water, but we can comfort ourselves with the knowledge that he managed to find true love and really help Rose in an extraordinarily brief period of time.