Your e-docs (Guest Ticket Booklet) will have a full sized luggage tag that you print out. It is usually one of the last pages in the file showing dotted lines for folds, 'staple here', etc. It may look small on the computer screen but when you print it, it will be large enough.
Here is a hint for using the paper tags: print out the number you will need and cut and fold them into the correct shape. Then get some clear packing tape and laminate the tags on both sides. Punch a hole on each end and get some tie wraps. Pack these in your carry on luggage. When you get to the hotel the night before your cruise, put those tags on your checked luggage and secure with the tie wraps.
Edit: I think your cousin showed you her Set Sail Pass which has an example of a luggage tag on it. You don't use that one. You access your online booking and download your cruise documents to get the full tag. On the "overview" tab of your booking you will see a box at the right titled "cruise documentation" with a "check status" button. It is below the online check in box, which is where you do your Set Sail Pass.