I hope someone else can explain better, but I will give it a shot (it was several months ago that I registered my kids online) You log into your cruise account online and click on something like "activities" or something similar (I just can't remember) There will be an option to register for the kids clubs, you just type in their age and if they are potty-trained (if a young child) and then you type in a password for use on the ship to get your child out of the club. Try not to forget it although I am sure they will remind you the first day if needed. You will also type in who is allowed to retrieve your child from the club. That's it! I am not sure how for in advance you can do it. I did it a couple months out. If it gives you the option to do it now, just go ahead, if it does not let you do it, check back periodically. Sorry I couldn't be more detailed. Hope that helps at least a little.