I’m using an older version of Opera (12.12) I’ve used it occationally for many years. Click on the Opera button (upper left corner) book marks should be there somewhere. To import bookmarks click the same button then go to settings->import and export. You will have to export bookmarks from Firefox before you can import them into Opera. Hope that helps
Since deleting Firefox and trying both Chrome and Opera, I am finding that both are much faster. I suspect my Firefox installation may have been corrupted through the years due to various toolbar Search trojans, etc that were installed/deleted.