Know the basics in defense and footworks first. Boxing is a full contact a contact sport. You don't want your azz got beaten bad in the first try.
You don't need really need to know much, I recommend bringing a water bottle, hand wraps, and a fully attentive mind to your surroundings, just listen to every and any advice you can get, you're taking your first step towards boxing, you're already making a good choice.
Pay attention...Put all your effort into everything you do, the coach will notice. Also stay after training and ask the coach questions and for additional instruction.
Who ever has a better left will win vs all the one arm fighters.
Keep your eyes open at all times, keep your hands up , dont turn around . And just try your best
Some tips, advices :) i have no experience whatsoever