When I use Application Loader, I get to the point where it asks me to \"Choose...\" the file to be uploaded.
If I understand correctly, it supposes to be the appName.app
Download the latest Application loader from here: https://itunesconnect.apple.com/apploader/ApplicationLoader_3.1.dmg. (Download the latest one. This doesn't get updated automatically. If you haven;t downloaded this recetnly you probably have a older version that may have errors which are solved in the newer version)
Then 1) Archive your build. 2) After your build archives, you will be in the builds page. 3) Export that build 4) Click "App Store blablabla" row 5) Save the file somewhere 6) Open Application Loader 7) click upload 8) upload that saved file.
Done.