If you have a ready app,
1) Choose “generic iOS device” (don’t choose any other devices connected or a simulator)
2) Go to Product –> Archive
3) If everything is fine, it should open the archive in the Organizer – there you can change the name of your upload if you wish. When ready click “validate” and then “Submit to App Store”.
*) When creating the next version of the archive don’t forget to change the version number from 1.0 to something different (it’s “Bundle Version” somewhere in supporting files)