Help with skys?

Well, one thing you could do is reference a photograph of a sky (via some search engine or something) to help you get a better idea as to what it looks like, and perhaps how to make one.

I'll try my best to explain. ^^;; (Note that I use Photoshop CS. Also, I do not have my Photoshop open while writing this, so it's quite possible I will make mistakes, or the result probably won't turn out as good, and won't be that detailed.)

I'll take this image as a reference. (If it won't link, I'll upload it to by Photobucket.)

You can either create a new document, or work in the wallpaper itself. If you do work in the wallpaper, create a new layer and move it to the very bottom.

Anyways, first of all, I think most skys have a gradient to them, from top to bottom, with the top usually having a lighter color than the bottom. From the image, you will notice that the very top is kinda orange-ish, while the bottom looks red. So take the gradient tool, choose an orange color for the foreground color, and red color for the background color (or vice-verca, since it doesn't really matter), then drag from the top to the bottom. If it comes out the opposite of what you want, go back and drag in the opposite direction. (Note you can hold the Shift key while dragging to make it go straight) If the colors turn out too bright, you can try adjusting the Brightness & Contract.

Next, the clouds. This shouldn't be too hard I think. Create a new layer above the Gradient layer and name it "Clouds". Go to Filter > Render > Clouds. Next, go to Select > Color Range. Click a black area on the clouds, and adjust the Fuzziness to 200. After you click Ok, delete whatever you selected (If there seems to be greyish areas still remaining, you can fix that by changing the Blending Mode of that layer to Screen). Now, seeing how the clouds are stretched, we're gonna do that too. Press Ctrl + T, so you can transform the clouds now. Increase the percentage of the Width (this option should be one the top) until you think it looks good enough. Then click the Green Checkmark on the top right to finish the transformation. Seeing how the clouds are yellow, right click the "Clouds" layer, and choose "Blending Options". Select the Color Overlay text on the left side (the TEXT, not the box. The right side should change as a result.) Give the Color box a Yellow color, and change the Blending Mode to whatever seems to suit the sky most. You can also adjust the Opacity if the effect is too strong. Click Ok.

Now, for the ground. Just create another new layer above the "Clouds" layer, name that "Ground", and go for a dark brown box right now. Honestly, I don't know I specific way to make a realistic mountain-ish ground. ^^;;

Finally, the Sun. This should be pretty easy. Again, create a new layer above the "Clouds" layer, but before the "Ground" layer, and name that one "Sun". Select the Brush Tool. Right click, and select one of the solid round brushes at the top. Give it a Diameter. Say...something like 100 seems fine for this case. Now, change the forground color to white, and just click on where the sun should be, and there's your sun! Well, almost. Again, right click the "Sun" layer, and choose Blending Options. This time, Check both "Outer Glow" and "Inner Glow". Feel free to adjust the settings of both Glows to your liking, then click OK.

Congrats! You've made a scene of a sunset! =D
Well, maybe only to me, since I did not try out anything. xD;; But if you have any questions, I can try to answer them. ^_^

Gradients usually turn out too regular for the sky (ie the colours are spaced too evenly for it to look believable.)

What I do is find a good reference photo, open it in PS (or whatever program you're using), then open your wallpaper file and start a new layer. Then, eyedropping colours from your reference photo, take a medium-sized, soft brush, and paint the sky while eyedropping from the reference photo. To get it to blend, try not to use smudge too much, you'll lose texture there. Instead, eyedrop intermediate colours and with a low-opacity brush, gradually blend the two colours.

If you use a soft brush, you'll get a very soft-looking background, like this (I used a photo for reference). Alternatively, you can use a harder brush, but with the opacity and flow set low, and brush over lots of times, using lots of intermediate colours, and get something like this (again, I used a reference picture for colours).

Clouds, I say don't use the default cloud filter. You get something that looks mechanical and not very cloud-like. Find reference photos you like, eyedrop colours, and brush it using the reference photo as a guide.

Okiyoshimoura

Heaven-Phoenix

MapleRose