From the Firefox browser, click on on the "Bookmarks" menu located at the top of the window. Next, click on the "Organize Bookmarks" option.
Step2
This brings you to a separate window which lists all existing bookmarks (favorite websites). From the File menu at the top, you have the option to Import and Export.
Step3
If you need to import external bookmarks and merge them into Firefox, do so by clicking "Import" from the File menu. This allows you to import your favorites from Internet Explorer, or just an existing file you had saved in the past. Choose the desired option, and hit "Next" to search for your bookmarks. When done, click "Finish."
Step4
If you need to externally save existing Firefox bookmarks, click on the "Export" option from the File menu. Once you choose a save destination, you're all set.
Tips & Warnings
It is recommended you make occasional exports/saves of your bookmarks once in a while, in case you need to suddenly format your drive, or any other unfortunate event occurs.