I haven't checked the actual web-site as I don't use Photoshop, but I love the effect and can see me using this myself. Where I pinned it from said "How to Create a "Double Exposure" in Photoshop — Daily Epiphanie"
great step by step tut on color correcting in PS & PSE with live video tutorial too from Snelson Snelson Padgett
use one tool in photoshop - Curves to lighten up your images, but it can make your colors and contrast pop by making an S curve. To do that, just add a second point in the curves window, and drag it down a bit.