To watch Live TV on your Telstra TV you can select the channel from the homepage under 'Live TV':
Or you can press the * icon on your remote to expose the 'Menu' and then select 'Live TV':
You'll then be able to select the Live channel you want to watch:
While watching Live TV you can change channels by pressing the up or down arrows on your remote and then press the 'OK' button to select the channel you want to change to: