Not a daft sounding question at all. Assuming since you asked about applying one to your signature, you already know how to change your signature by editing your profile, the rest is easy. Go to the Cruisetickers.com website (there is a sticky post on it at the begining of this section) Use that site to create the ticker of your choosing. Once you have it made there should be a button to "copy" the source code for the ticker. Be sure to copy the "BBcode" version, HTML will not work. Once you have the ticker copied, got to your profile and paste the code your copied into the end of your signature. Then save your profile. Assuming you copied correctly, everything else is automagic.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013