Yeah, the others explained where to navigate to import your saved html bookmarks back into your new FF install. Did you follow the steps?
Right click on the top bar on a blank space until you see where it says menu bar, like in the picture. Check it so you have the menu bar there, then go to bookmarks.
Then go to where it says Organize bookmarks.
Then go to where it says Import and backup, and go to Import HTML.
Click on that, then have from an HTML file and Next. then pick where your file is, on the desktop, and finish.