Dreamy Effect

Start by opening up an image in Photoshop, any photo should work. I'm going to use this landscape found in Google

Now press D to reset colors to Black as Foreground and White as Background and now press X to switch them. Go to Select -> Color Range and use the values below

Some parts of your image should now be selected as shown below

Still with the selection on, go to Select -> Feather and enter from 15 to 35 in the text field depending in your image, I'm using 20, and you should now have something like this

Create a new layer and fill your selection with white

And your image should look like this

Now change the blending options to Overlay or Soft Light and you're done