1. Run Firefox after installation of the program. You will see a dialog box showing that OneStop Video Converter addon is installed. Just close this dialog.
2. Right-click on the Firefox toolbar to call the context menu and select "Customize".
3. This will call the toolbar customization dialog. If you scroll down, you will see the OneStop Video Converter icon.
4. Finally pick the OneStop Video Converter icon with your mouse and drag and drop it on the Firefox toolbar. Then click "Done" to close the dialog.