When putting on the shelf, select the certificate file and description file corresponding to the release version, and package it. After the package is completed, you can submit it at the Upload app store button of the Xcode software, or you can select the AU (Application loader) software to upload the ipa package. There are two ways. You can try it out:
The following is the official AU tutorial: Click to open the link
The pit that is easy to step on here is
1: Apply for the Itunes connect app first. The app is closely related to the appId you applied for. Make sure it is correct.
2: There is a problem with the certificate
3: The icon icon is incorrect. For 1024icon around Xcode8.3, please add the icon when submitting for review. After Xcode8.3, drag the 1024icon in the corresponding place in Xcode, just change the name of the image to iTunesArtword@ 2x.png, note that this icon cannot have transparency when the Mac is submitted, the png image is transparent by default; the method to remove the transparency:
a: Change the picture in png format to jpg format
b: Export the image in jpg format to png, or uncheck the alpha channel under png
4: The IOS SDK version is incorrect, at least the version is required to be 11.0, and the ios SDK around Xcode 8.0 is 10.0, so an error will be reported when uploading, and Xcode needs to be updated