Caoedhen
Put anything in the colors you want close to the camera and take your shot of something further away.
This isn't magic, it isn't an effect added afterwards, it is poor framing of a shot capturing some sort of colored rings close to the camera.It is distracting more than anything.
?
The way this was done was by having a colorful item or items in the foreground and then focus on the background so that the colorful items are outside the depth of field.
myydcp
You can add an overlay layer of rainbow in photoshop.
As for the layer, you can search “overlay rainbow” on google.
Overlap the images and turn the rainbow into “overlay” or “screen”. (Or other overlapping types if you like.