1. Open the picture that you want to add a rainbow on.
2. Make a new layer.
3. Take the Gradient Tool. Choose the style Linear Gradient – TransparentRainbow.
4. While pressing down the Shift key, make short vertical stroke in the middle of the picture. The direction should be from top to bottom.
5. Choose Filter - Distort - Polar Coordinates. Tick Rectangular to Polar and pres OK.
6. To move the figures use the Edit - Free Transform (Ctrl + T). This way you can reduce or increase its size and move it to the appropriate location according to your picture.
7. Choose Filter - Blur - Gaussian Blur with Radius: 4.5px
8. Change Blending Mode to Screen and low the Opacity to 80%.
9. Take a large soft round Brush with Hardness 0 and delete where you think it is necessary.
10. Your rainbow is ready.