TRANSPARENT BOX

(1) First, you'll need to open up an image. I chose a blend that I was going to use for something and I never used it.
(2) Next, make a new raster layer.

(view screenshot)

(3) Okay, so you've got the new raster layer, get the Present Shape Tool out and set your settings to match mine:

(view screenshot)

(4) Choose the colors you want. Your main color will be the outline of the box. I want the outline for mine to be black.

(view screenshot)

(5) Now make a rectangle anywhere on the image.

(view screenshot)

(6) ALMOST DONE! Now, the box should actually be on "Vector 1" Set the opacity for Vector 1 to 70 and the blend mode to normal.

(view screenshot)

(7) Now, of course, you can add other effects and add some extra coloring.