I don't think it can be explained in a few words.
There are too many variables.
Here is a link to 20 different tutorials on the subject of layers:
http://www.graphic-design.com/Photoshop/tutorials/0409-06.html
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I am a Photoshop user. Can anyone help please on the subject of layers? It's something I have never understood. If possible could someone just tell me, in a few words, how to build a layer? Thanks and a happy Christmas.

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