Go to Saipan, 3G, catch fish, Skynet, any of them will work, but I’d better go to 3G, it’s faster. Submit your mobile serial number. After the certificate is prepared, download it to your mobile phone and use X Manager to unzip it, and you will get the certificate and key. Download a software and sign it freely. Open this software and import the certificate and key to sign the software. The specific operation is not too complicated. One look and you'll understand.