To get started, install the Archive Facebook extension from the Mozilla Firefox Addons gallery. This is an experimental extension, so you will need to enable the option to allow you to download and install it.
After restarting Firefox, you should see a new menu item “ArchiveFB” in Firefox between the Bookmarks and the Tools menu..
Go to ArchiveFB > Show in Sidebar and open the sidebar.
While you are seeing Facebook open in your browser, select ArchiveFB > Archive. You will automatically get redirected to your Facebook profile page and see the following dialog box:
Select OK to start the backup process. Cancel will not start any operation. Once you start the archive process, ArchiveFB begins to retrieve your Facebook stream in reverse chronological order. You will see a series of dialog boxes displaying how far back it has progressed in the retrieval process.
If you select Cancel on any of these dialog boxes, your archive will extend back in time only till that date and time stamp.
Once the retrieval process is complete, ArchiveFB will start downloading your Facebook data to create your backup archive.
The process may take several hours depending upon the speed of your connection and how long and extensively you’ve used Facebook.
Be patient, but if you find that the process is stuck on one particular item in the list, click Pause and then Start to resume. I found that this trick worked when ArchiveFB seemed to get stuck on a few items in the list.
Once the backup and archive operation is complete, you can see a new entry in the sidebar “Facebook | username date” with your username and the current date. This indicates that the operation was successful.