Log into your iOS Development account and click on the iOS Provisioning Portal link at the right hand side of the page. In your Provisioning Portal, click Devices in the left tab bar. Click the add devices button at the top right of the page. Here you will need the device's name and Device ID. To get these connect the device to your computer and find it in iTunes. With the device selected click on the device's serial number, and it will switch to the Device's Identifier. Then click Edit > Copy Identifier (UDID). Now return to your Provisioning Portal, paste the identifier and enter the name of the device.