In general terms, menu options are grayed in any computer
program whenever the context of that menu item is not
appropriate. An example would be the Edit menu would not
be appropriate in a word processing document if you had
not opened a document to edit.
With that new found knowledge let's tackle Front Page.
Since you are a student and attempting to learn, I will
give you some clues and let you figure it out.
Open the Front Page program but do not open a webpage.
Take a look at the pulldown menus across the top of the
screen. Pull each one down and read which ones are and
are not available due to the context of not having a
webpage open.
Now open one of your web pages and repeat the pulldown
menu process described above.
Now for your problem: the Custom Link Bar will eventually
wind up on a webpage. What do you think you have to do
prior to Front Page letting you add a new Custom Link Bar?