This is really awesome effect if you want to make any picture look softer or slightly glowing, so find the picture you want to edit using File>Open I chose this picture, you may want to use it too.
In the right-bottom corner of photoshop you see Layers, and the Background layer in it. Right click on it and select Dublicate layer...
You should now have another layer item called Background copy
Now go to Filter>Blur>Gaussian blur...
There should now be new window with settings and preview Set radius to something like 3 if you're using small image (around 640x480), select value depending on image size, I'd use 15 - 25 for 4000x3000 resolution photos.
As you can see image is really blurred, but that's not really our intention so find Layers again in bottom-right corner of Photoshop and right click on Background copy layer, select Blending options...
And we got another window popping up in Photoshop Now you have to select Blend mode to Screen and Opacity to 70 or so.
(By the way you can try various blend modes such as Normal, Darken, Lighten and so on)
It's finished, you've made a nice soft glow effect!
I probably could have used better photo which accents the effect more, but you should have some idea how it looks now.