hatstead • Adobe Community Professional, Aug 10, 2020
Go to File>new>blank file. Enter the width and height to accomodate the 2 pictures, resolution 240 px/in, background to suit. This will be your canvas.
Go to File>place and point to picture file A, click on Place. Position A on the canvas. Note A will be on its own layer. You can make minor size adjustments with the corner handles.
Do the same for B
That should do it.