That option is part of the bookmarks library or bookmarks manager:

• use Firefox Button -> Bookmarks -> Show All Bookmarks
  (Or keyboard keys Ctrl+ Shift +B)
• see importing Internet Explorer Favorites from another computer <-- clickable link --
  similar if IE on same computer, includes screenshots of what to do

Post back with how you get on, does that work ?

Hello John,

Thanks a lot for your solution.

It resolves my problem completly,

Kind Regards,

Sjaak Witteveen

Glad to have helped.