How do I re-size a layer without resizing the background I am pasting it on?

I have a certain sized jpeg file (3648 pixels X 1368 pixels) that I want to use as a canvas to place smaller jpeg files on.  The problem is, the "smaller" jpeg files are actually bigger.  Rather than shrink them down individually and then paste on the canvas, I would like to copy them onto the canvas and then shrink them (this will allow me to more easily compare their size to the other photos as I'm shrinking them).
Is there a way to do this in Adobe Photoshop?


When you say "Grab the corner handle and drag smaller" I know what you mean since this is how I would do it using MS Paint.
The problem is, I don't get a corner handle to show up.  If I hold down the Shift key, it merely prevents me from seeing the movement until the movement is complete (i.e. as I move the 2nd image where I want it, the screen automatically shows where it is being moved to whereas holding down the shift key merely moves an outline around which, once the shift key is released, becomes the location of the 2nd image).
I should mention that I am using a Mac and not a PC.  Is that why there is no corner handle to grab?