To start with, add your images from the last lesson to your gallery.
Gallery task - to keep adding to
This lets you add a second image as an overlay. Here I've used a rainbow flag, but you can use any image.
Here are the instructions for this.
You need both of these images for this.
This is tricky.
Not every image you find on the web will open in Photoshop. And lots of them will be really poor quality.
Use Unsplash to source your own images. These will all work and are really high quality images. They're also totally copyright free, which is a bonus.
You can go back to lesson 2 (working with colour) if you need to.