Merging 2 photos

[hartpaul]

With the Pan tool active just clicking on the title of that image or any part of that image - the color of its title bar will change from light blue to dark blue showing that that image is active if you need to change size , do an adjustment, apply an effect. Go on have fun load up 4-5 images and practise making each image active in turn.
Note also that as you make each image active, the thumb in the Levels palette changes to represent the active image.

Note also that as you make an image active , you can also drag its layer thumb over and on top of any other image in your workspace and it will make a copy of it on top of that image. So it will appear that you have two copies of the same image , but making each image active you will find that one has two layers and the other only one.

Note also in answer to the question posed at the bottom of your first post -
2 how to create a new layer.

Bottom left of the Layers palette - looks like a curled page - hover over it with your mouse and it will show 'New Layer' - clicking on that will show the different types of new layers you can produce. You will probably need a New Raster Layer - the most common one - that is why it is on top.
Again play around with it to find out what it does. All it costs is a bit of time.