There is no channel tab in Elements, you need the full version of Photoshop CS.
Depending on what you want to achieve, you can work with layers and the levels adjustments in Elements to get greyscale layers for each channel.
In the levels dialog you can select channels : set the output of the non selected channel to 0 - 0 instead of 0 -255 (bottom slider). For instance, if you want the green channel, you can neutralize the red and blue channels. The resulting green component may be set to greyscale (Shift + Ctrl U).
Are you trying to add an alpha channel or see one that is already there?
If the channel is there already.
You could go to Select>Load Selection of the channel with Invert checked, make a new blank layer, Edit>Fill Selection>Black and then Select>Deselect.
(the channel may be of another name besides Alpha 1)
Now add a white fill layer below and that should be a representation of the channel in the layers panel.
Maybe if we knew the gist of the tutorial your following, we could give more specific advice
Message was edited by: R_Kelly