It's easy! Press the green button once you have highlighted the channel you want to lock on the TV guide and then enter your TV PIN. A lock icon appearing next to the channel name indicates that the channel has been locked.
To unlock, highlight the channel that is locked on the TV guide - you will see a lock icon next to the channel name - and then press the green button on your Digicel remote followed by your TV PIN. The lock icon will disappear, indicating that the channel is now unlocked.