How to backup Firefox bookmarks

follow instructions:

Backing up your bookmarks is very important. By doing this regularly, you will be able to retrieve your favorite URLs in the event that your personal computer crashes.
Bookmarks are a way for you to store and manage popular websites you visit directly within the Firefox Internet browser. If you have to reinstall Firefox, you may lose some of your personal data. However, Firefox creates backups of your bookmarks regularly. You can restore Firefox’s bookmarks to a previous set of bookmarks
Backing up your Firefox bookmarks is certainly preferable to having to search for your favorite websites again and building up your bookmark list from scratch.
You keep your valuable resources bookmarked which you need to access often to get new information or get things done.