UPDATE: Guys Now you can hack your phone so you will not require the certificates anymore.Read my post "another symbian hack" and hack your phone. HERE
For Signing Applications For S60v5 Devices first you have to get a Certificate and Key file
This tutorial will help you to get your Certificate And Key Files.
1. Go to http://cer.opda.cn/en/index.php
2. Click Register3.Enter Your Required username and password and create an account for you in OPDA4. Then Login To Your Account
5. Then Click to Apply For A New Certificate
6. Then Check The status Of your certificate It takes 24 hours for the certificate to be ready.
7.Log in Again And Download Your Certificates and Key