You app will be a free download on the App Store and the Google Play Store (Jan 2015). Customer's can access your app by searching your business name on the App Store/Google Play Store or if they select a unique link whilst on their mobile device.
As more people download your app it will 'move' up the Store listing and become easier to find.
To find your app's unique URL.
Google Play (Android):
Go to play.google.com/store search for your business name.
Copy the URL just like you would for any website.
App Store (iOS):
Open iTunes and type in your business name in the App Store search-field in the top right corner.
Click on your app and then select the arrow, followed by 'Copy Link'