Learn to remove the background of raw images using magic wand for images with organic subject and plain color background.
Learn to remove the background of image with geometrical form subject or an image with scenery or complex colored background.
Adjust the size of image by using "Ctrl + T" / Transform to scale/ stretch image as well rotate the Images
Drag the image to other photoshop file and adjust the image layer sequence accordingly to move images above or down.
Next to the properties panel in the "adjustment" panel the colors, saturation, concentration, brightness, contrast and such can be adjusted separately.
Opacity of individual images can be edit accordingly to provide a fading effect within the composition