Tekniko I don't know about iOS but for Android the process goes like this:
Export game as CocoonJS > Upload it to CocoonJS > Download it back to your PC > Create a Keystore file (Make a backup copy, and keep it in the cloud or on a flash drive) > Sign your .apk file > Zipalign your .apk file > And then its ready for upload to Google Play.
The first time through may seem like a painful process but it gets easier.
Here are a couple good tutorials to help you through the whole process:
To update your game you will have to repeat everything except for creating a Keystore file. You need to use the original Keystore file for the life of your game. This is why you should make backup copies, and keep them on flash drives or in the cloud someplace. If you were to loose it I don't think you would be able to update your game again.