Just checking. Did you follow
these instructions?
Installation is simple: Unzip the eq2ui_journals_infocenter.xml and eq2ui_journals.xml files, and the "infocenter" folder (with its various subfolders), into your custom UI folder.
(If you don't already have a custom UI folder, then you need to create one and tell the game to use it. Instructions for doing so can be found elsewhere on this site.)
Once you're in the game, you can call up the info center any time you like by typing "/show_window Journals.InfoCenter" (or by creating a macro to do it for you).