Disclaimer: This tutorial will only be demonstrated for use in Photoshop.
Open a new document in Photoshop to get started (Any size - but for the purpose of this tutorial: 500px x 500px. Go to here or here and look for screencaps that I want to choose. I pick 5 that I want to use. One of the 5 will be used as a bacground image. I drag that one onto the canvas. You can resize to your liking. My result. 
For the other screencaps, I used the Sun Glare coloring I made. If you don’t have this, you can simply download it from my [resources] page. Open the coloring in Photoshop from where it’s located on your computer. Once opened, you will see a folder and a picture thumbnail in Layers palette. You replace the picture example with one of 4 other screencaps. Then go to Layer → Merge Visible (SHIFT + CTRL + E). Keep doing the last 2 steps until you done it to each of the remaining screencaps. I then resized all the screencaps to a width of 200px (constrained proportions must be checked). I dragged each screencap into the original 500px by 500px document we started with and aligned them in the middle of the canvas atop of the background screencap like so. 
As you can see the 4 screencaps are a vibrant color where as the background image is rather dull. To fix that, I selected the eyedropper tool (press I and it will automatically switth to it), selected a sample color from one of the vibrant colored screencaps. I got this color #e6d600. I selected the background screencap layer and press & hold: SHIFT + CTRL + N (creating a new layer in between the layers). The new layer should be selected. You will now use the Paint Bucket Tool (press G) and click once on the canvas. It should have filled the canvas with the color you selected. I changed the blending mode of that layer to overlay and an opacity of 90%.The result was this. The background screencap should be the same tone of the others now.
I then you used some of my textures (located on my resources page) to spice it up things a little. I dragged this [x] found in texture pack 04 and this (with a blend mode of Lighten) [x] from texture pack 05 between the color and background layers to give me this. 
Optional: I selected the top layer in the layers palette and created a new layer (SHIFT + CTRL + N). I used the brush tool (Press B) to create a feather vignette. Make sure the brush size is 150px with a hardness of 0% and line the edges of the canvas. I then set that layer to the blend mode: Color Burn. Resulting in the final graphic in this tutorial.
You did it! I’m proud of you. I’d like to see results. :)