To save your bookmarks, you don't need to pull up any folder. Here's how you save the bookmarks in firefox:
1) In firefox, Click on Bookmarks-> Organize Bookmarks. This will open up a Bookmarks Manager window .
2)In the Bookmarks Manager window click on File-> Export . Now just browse to where you want to save the bookmarks and hit save. you can also directly save them(by browsing to the paths of course) onto a floppy disk if you have it inside ur floppy drive or a pen drive if you've attached to your system. Or you could just save it on ur local hard drives and then copy the bookmarks file onto a removable device if you want.
That's it, now you got your current bookmarks manually backed up.
To restore these manually backed up bookmarks in case you lose them,here's how you restore:
1) Follow the steps which i described to open the bookmarks manager window
2) In the bookmarks manager window click on File-> import . Choose 'from file' in the dialog box which comes up and hit 'next' and select the file which you had manually backed up.
That will restore the manually saved bookmarks.
To answer your other questions as to where the firefox bookmarks are stored :
They are stored in a file called bookmarks.html which resides in the profile folder of firefox.
To go the profile folder , click on Start-> Run and type %appdata% This will open the application data folder or the appdata\roaming folder if ur in vista. From here browse to Mozilla-> Firefox-> Profiles -> 'profile folder' which will be named as cwxn84oa.default for instance (could be anything.default) .
In the profile folder you'll see the file bookmarks.html . This is the file which has your current bookmarks.
Here in the profile folder you'll also see a folder bookmarkbackups. Go to this folder. here you'll find that firefox automatically backs up the last five days worth of bookmarks!
If you want to restore any of these bookmarks files, follow the steps i described as to how to restore (file-import in the bookmarks manager window and browse to one of these bookmarks files)
that's it :)