Publishers face this problem when launching a mobile version: how to let existing readers know about e.g. iOS Newsstand app.
Here are few examples that we find working. Some of them require you to sign in for Apple Developer Account. You can do that without paying $99 annual membership and still download those materials. We could just copy those materials for you but they change from time to time and it is better that you have always the newest one. If you wish we can always email you the newest one.
We have covered only technical issues here but will write another post about best business practices when launching on mobile.