Further to #17 I am confused as well becuase I believe we have people explaning various uses of layers/adjustment layers/layer masks and the different approaches would confuse anybody. You started off with a 'simple' task of combining five birds, each in their own area of the picture and rather than using a simple paste technque for most flexibility you need to keep each bird on its own layer so the command when you copy each is 'Paste as a [new] layer" or however adobe calls it. You end up with the chest of drawers with each bird in its own drawer/layer and each can be moved around to achive the composition you want at any stage [ within reason ... you will quickly find exceptions to that topwards the end of the process ]
However to see bird five in the bottom drawer you have to have 'holes' in the upper four layers where you have positioned it.
A small party went with Sue on her 90th birthday to places she remembered from younger days. Each segment was on a separate layer including the title which is a vector layer as opposed to photo raster layers.
We next I think start talking about adjustment layers which as said is a layer which contains the modification data [ I believe how RAW adjustment works except it is a separate file linked to the original file ? ]. The default setting in my programme has this as a pure white image in the layers palette and when I apply black paint to remove the effect [ or moderate it using a tone between Black and White ] it appears as a black mark in the Layer Palette and I can see the original image through the modified view from the AL being on top of the picture.
Here for purposes of this thread is a shot of my wife feeding a gull and I applied an adjustment layer using the threshold tool which converts it into either black or white depending on the original tones. I then used a black brush to paint the AL[T] layer to reveal the original bird underneath [ not a good example as the underside of the bird's wing was rather dark. but you can see some tone in its tail feathers. Early on in discussions I mentioned the ability to flood fill areas with a partial tone to partly modify the effect of the AL[T]. So to illustrate this I flood filled the top right quarter with a light grey and the bottom right quarter with full black to show what the original photo was.
I will pass on Layer Masks becuase I have only used this superior technique once but really it is like using an adjustment layer to mask out part of an image with black showing/hiding and white hiding/showing depending on how the programme is set up to work. In PSP I have the option of working either way but yet to work out whyI normally use an erase brush which is a destructive process and definitely an inferior way to go