Uploading an ipa file

I did not use XCode to output the ipa file. However, I have not done any signature-related work, and I would like to sign the file with XCode. Since I only have the ipa file, I can't register it in the archive, so how can I get it ready for upload?

I have the provisioning file, certificate and key ready to go.

Uploading an ipa file
 
 
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