Copying, pasting Favorites from file to Firefox

I recently switched to Firefox from IE. I have an unusual problem: I want to literally copy and paste into FF Bookmarks a huge number of old Favorites I copied ages ago from IE and pasted into a separate regular file I call "Favorites all" that I put under My Docs. This is a regular file document that I can even print out with a directory printer (not the "Favorites" in Docs & Settings). I want to be able to literally copy all of them from the regular file and paste them into my current Firefox Bookmarks, so that I'll have all my many bookmarks from the past in FF. I've already imported the current IE Favs I had before I switched; I'd like the FF Bookmarks folder to contain all favs I've ever had and have tried to select all and copy them and paste them into FF. Doesn't work that easily. I have a feeling this is something I won't be able to accomplish. I'd appreciate any ideas you all have on this strange action I'm trying to perform. Thanks. ec
Sorry, I didn't give contact information to receive emails of any replies.