Grids are such a popular thing in images, and i'm going to show you how to put images onto your image ^^ My tutorial is a bit different than everyones too, because i use mine a different way!

1 Just for this tutorial, use this image of mine.
2 Select all of the image, copy it, and then open a new image. [the size will be on there already] and then paste it!
3 Create a new layer. 4 Now, minimize that, and create a new image. the new image will be your grid pattern. Now, depending on how big you want the grid to be, make a new square document. my new image is 5x5. 5 Take the pencil tool, and make it 1px. now, Select a color of your choice [I'm doing white] and draw one line on the right side and one on the bottom like the following:

[I have magnified mine by 1600% and ignore the border. I put it there so you can see it better!]
6 Okay, keep it open and go to edit, define pattern. name the pattern grid or something.
7 Now, back to the image you want the grids on.
8 Once you have that open, select the pattern stamp tool.

[Click on the stamp and hold down, until you get to the pattern stamp tool!]
9 Okay, a menu thingie should pop up on the top. Where it says PATTERN, click the down button and find your grid pattern ^^
10 Choose a brush size and opacity and color all over your image where you want the grids to be =) Keep changing the opacity to make it different in areas.
11 If you mess up, just use the eraser tool ^^ Now you can go pretty grids!! =D