The Photoshop tutorial has the following effect chart:
1. Create a new 500x250 canvas. Create three new groups in the canvas and send a picture in each group. And then cropping it once (the goal is to get rid of the extra parts) as shown:
2. Create a new layer, name it as a rectangle, and then lock the layer with the rounded rectangle tool to create the image.
Create a new four layer, name each layer (easy to remember), and then alt+delete fill each layer. After filling, enlarge the canvas (image-canvas size) by 10 times times and put four layers in the following figure.