You've decided to check into a room at a motel instead of going home. You can look around, go out on the balcony and interact with a couple things around the room, but the main point of interest is the shoebox you took out of the locker at Lexington Station. Sit down at the table and open the box to reveal a bunch of origami figures, a handgun, a phone and a memory card. If you look closely, you'll see that the figures are numbered. You can inspect the gun or the origami figure, but you'll need to check out the gun first if you want to do both. Once you check the origami bear, you'll open it up to reveal a message and another ticket inside. This time you're told to go to an auto shop. Next inspect the phone and plug the memory card into it to reveal another message.
This is the beginning of the main storyline with Ethan: you must pass certain trials set out by the Origami Killer to earn letters to the address where your son is being held. If you can complete all the trials, you'll get the full address. The trials will test your resolve and your love for Shaun. The motel is now your headquarters, and you'll return there whenever you finish a trial to open up the next origami animal.