2. Click the "Menu" button in the top-left corner of the window.
3. Select "Settings" from the menu.
4. Click on the "Extensions" tab in the left sidebar.
5. Scroll down to the "Plugins" section.
6. Click the "Enable" button next to the plugin that you want to use.
7. Restart the Opera browser.
The plugin will now be enabled and you will be able to use it with the Opera browser.