You can easily import bookmarks from Opera to Firefox.(Import bookmarks in Firefox)

              You have been using Opera browser, but switched to Firefox as Opera doesn’t support sites that are created for a particular browser, especially many of the banking sites. You had saved many bookmarks in Opera and want to import the same in Firefox.
              Importing your bookmarks form Opera to Firefox should be fairly simple. Firstly, create a HTML fi le of your bookmarks in Opera. This can be achieved by exporting the bookmarks from your Opera browser and saving it as an HTML fi le. Open Opera browser, go to File, under that you will fi nd the option Import and Export. Click on it and then select the option Export bookmarks as HTML. Select a location and save it. Now open Firefox, select ‘Bookmarks’ tab. Here you will see the option ‘Organize Bookmarks’ under that select the option Import and then select the HTML fi le from the location where you have saved it.