First obviously you have to have Firefox web browser.
OK Here you go.
(click images to zoom in if needed)
First open up your Firefox web browser and click the Bookmarks tab on top of browser.

Exporting / Importing your Firefox Bookmarks as a backup file
Once you select the bookmark tab, then at the top of the list select "Organize Bookmarks" and you will see a new window pop up. that loooks like this:

Exporting / Importing your Firefox Bookmarks as a backup file
Now you want to collapse all the the left side to there there is just one folder showing by clicking the plus or minus sign next to the very first one should be titled "Bookmarks" once its collapsed. Then Highlight it by clicking on it. as shown below
so it looks like this:

Exporting / Importing your Firefox Bookmarks as a backup file
Once you do that then select the 'file' tab on top of menu / bookmark organizer, the click export.
A save menu will come up then slect on that save menu on the left side of it 'desktop' or 'my documents' tabs which ever or where ever you want to save them to. Once you do that then keep the file name the same as it should say 'Bookmarks' and it will be in HTML format already. I would suggest adding to that file name, not change it but add to it a date at the end of it so it would look like this 'Bookmarks 08-01-08' with out the ' ' inthere of course but that way the more times you back up which its always good to do at least once a week or maybe 2 a mouth depending on how many things you add during that period of time that they and your bookmark back ups are filed and organized the best and to the newest so you can figure out which one is what and what one is better or newer to use etc etc... Then jsut click save and it will export them to the file you placed them in.
I myself made a folder a head of time and have my own "important address's and bookmark folder" that i save them in each time. That is also another good reason to add the date to them so that you do not overwrite the older one just incase you lose one you still have the others to go back to that at least still have most of your bookmarks in them and that way if you lose any it may be only just a couple you lose instead of all of them.
There you go, i hope that helps and you keep your items backed up and your goos to go..

PS~
Firefox also saves a (so called ) back up copy of your book marks every so often on its own which is located in a different computer file . path of its own.
C:\Documents and Settings\
account name\Application Data\Mozilla\Firefox\Profiles\asrm8d6u.default\bookmarkbackups
That will be in another tutorial regarding this though as this tut is done and that one is regarded un-hiding hidden computer folder to be able to find it / them. Hope it helped some of you and you learned something from it and enjoy.
Also i did this tut the way i did that way with the items all closed you will be sure to back up everything including your bookmark tool bar items, If done other ways it could / would only save / back up certain ones instead of EVERYTHING

Ok thats it. Have fun and back yo stuff up yo, always be safe, better safe than sorry as they say right? lol