First, after you download the certificate, you must download a key file. After you get these two files, you download a free signature software on your mobile phone and install it on the C drive. After success, open the data management of the mobile phone and find the folder of your mobile phone disk, that is, find the freely signed file: freesing. Then put your certificate and key file in this folder, and then exit. Open the free signature software and sign it yourself ~