Yes, the only way to upload your .ipa file to iTunes Connect is with a mac using the latest OS X 10.9 and the latest version of Application Loader which is bundled with X-Code 5. The .ipa file has to be on the mac, you can copy it from your PC to a flash drive, then paste it to the documents folder on the Mac. I am assuming you have rebuilt your app with an app store profile otherwise it will not be accepted. Before you upload the file there is other stuff to do like screenshot uploads and meta data, this is most important as they will reject an app just for a bad description.