To acquire the distribution certificate:
Log in to the iOS Dev Center.
Navigate to the iOS Provisioning Portal.
Click the Distribution tab.
Follow the instructions to create a new certificate that will be used
for distribution. The process is identical to that which you used to
create your development certificate.
After the certificate is issued, download the .cer file to your
computer. Create a P12 file from your private key and certificate.
Once you have the distribution certificate, you will need to create a
distribution provisioning profile:
Go to the Provisioning section of the iOS Provisioning Portal.
Select the Distribution tab.
Create a profile for the App Store distribution method.
After the distribution provisioning profile is created, download the
.mobileprovision file to your computer. Keep this file in a handy
location for later.