Before a developer can send you an application for testing, they must register your device with Apple under their application-testing program.
To send your device ID to a developer for test-program registration:
1. Launch iTunes.
2. Connect your device to your computer.
3. Select the device in the Devices list.
4. In the Summary pane, click the Serial Number label. It changes to Identifier.
5. Choose Edit > Copy.
6. Email your device identifier to the developer.
Be sure to include your name and device name in the email.