In the channel selector you can choose which channels to add to the Active Channels list on the right. You can simply double click on them to add the channel to the Active Channels list.

When you select one or more objects in the object list to the left of the channel selector, you will see displayed here a list of all channels that are available for this particular object(s). If you select two objects that have partly different channels - like a light and a camera - only the channels will be displayed that the two objects have in common.

You can filter the list with the channel filter pulldown menu at the top of the list.

At the bottom of the list is a checkbox. Display Animatable Only. When checked only the animatable channels and objects (green triangle on in the Animator project window) are listed above.