Bookmarks - How to import the FireFox bookmarks
This article explains how to export your bookmarks to an HTML file, which can be used as a backup or for importing into another web browser.
Click the Library button on the toolbar.
Click Bookmarks.
Click Show All Bookmarks.
Click the Import and backup your bookmark icon, then click Import Bookmarks from HTML...
Select the location in your OneDrive to import the files from, then click Open.
Your bookmarks are now imported.