First, if you want black and white images in the channel, both black images and white background images, go straight to the above mentioned, select/copy/paste them all.
Second, if you just want the white or black image in the channel, hold down Ctrl and click on the thumbnail of the channel panel (the channel layer you need). After calling up the selection, you can see if it is you. The desired range, if it is not the desired range, unselect ctrl+shift+i, then copy (ctrl+c) and paste (ctrl+v)