If you can not find your app on the mobile device first make sure you have completed the creation process by clicking 'Create my app'.
The search function can be found in the "Search" tab on your device.
Type the name of your app in the search box.
After a few seconds Apps matching the name will be displayed.
You can find a link to your app in the email you received from 'firstname.lastname@example.org'. (Please check your spam folder.)
Click 'Start your App' on the device - you want to run your new app.