Travel illiterate can you guys give me some pointers?

Been atleast 7 years and I don't travel enough to really know protocol. I'm taking a trip to LA in a few weeks and I booked and paid for everything online. It's gonna be a short 3 day trip. I leave at 3pm. I plan on just taking a small backpack. Going for pokemon go and im also taking 2 portable chargers. Flying into LAX. Am I gonna get emailed tickets or do I have to print them out and stuff at the check in counter? Has anyone traveled to LAX and have some pointers?