Just go to their web-site, http://www.royalcaribbean.co.uk/countryHome. and follow the instructions.... Neil.
Go to the website as detailed below, then click on the tab," before you board", there you will find online check in, you will need your passport details to hand and a credit card, doing this makes it quicker in line when you get to the port. you just need to print out.
With perseverance. It is not the easiest website to use. I had lots of problems but got there eventually. Keep trying.