How to Back Up Your Bookmarks on Mozilla Firefox
Start the Mozilla Firefox browser. Make sure you have added any bookmarks that you want to be included when you back up your bookmarks.
Choose the "Bookmarks" menu and click on "Organize Bookmarks" to bring up the "Bookmarks Manager" in a separate window.
Select the "File" menu from the "Bookmarks Manager," and click "Export" to open the "Export Bookmark File" dialog box.
Use the "Save in" drop-down list and select the folder to which you would like to save the backup copy of your bookmarks.
Click the "Save" button to close the "Export Bookmark File" dialog box and save the bookmarks as an .html file in the location you have chosen.
Close the "Bookmarks Manager" and return to Mozilla Firefox. You can now browse normally, knowing that you have created a backup of your current documents.