1. Open your phone's web browser.
2. Go to the Opera Mini website: https://www.opera.com/mini
3. Click on the "Download" button.
4. Select the "Other versions" option.
5. Scroll down to find the version of Opera Mini 3 that you want to download.
6. Click on the "Download" button next to the version you want.
7. Follow the on-screen instructions to install the app on your phone.
Alternatively, you can download an old version of Opera Mini 3 from a third-party app store. To do this, simply search for "Opera Mini 3" in the app store and click on the "Install" button.
Please note that downloading apps from third-party sources can be risky, as they may contain malware or other security threats. Only download apps from trusted sources.