I assume you are talking about screenshots. If that is the case, it is actually quite easy to find and view them.
First you must go to the directory of where you have Play Online installed. In my case, the path is: C:\Program Files.
After finding the PlayOnline folder in "Program Files", and clicking a couple of times, you should arrive at a screen with three folders within the directory C:\Program Files\PlayOnline\SquareEnix, in my case at least. They are "FINAL FANTASY XI", "PlayOnlineViewer", and "TetraMaster".
First click on the "PlayOnlineViewer" folder. At this point, you will see various other files and folders. Simply click the folder named "pub".
Then you will see some more folders, so click the one named "home01". Again there will be some more folders. Now click the one named "open".
After that, click a folder named "ScreenShots", then a folder named "FinalFantasyXI", and voila, all the screenshots you have taken should be there =:D.
Again, the path is:
C:\Program Files\PlayOnline\SquareEnix\PlayOnlineViewer\pub\home01\open\screenshots
You should note however that this directory is based on my own personal installation of the game. If for some chance you cant find the screenshots in the "home01" folder section, try any others that are there, like "home00" or "home02".