I'm quite busy with school now but wanted to pass on my knowledge to those who are in the business of creating desktop wallpapers. doesn't matter what OS as this isn't Os specific except what file format you save them in.. .JPG or .PNG.
if you are going to shoot photos of nature, landscapes which, seem to be the popular for wallpapers, here is some advice on shooting photos with acceptable focus from fore to background. my recommendations are based upon the assumption that you are using a full frame sensor DSLR.
EF lenses have a window with which you can adjust the focus for certain distances. for a full frame sensor camera, say a Canon MarkII or MarkIII. same goes for Nikons.
Use a tripod. using a tripod is necessary because you'll be shooting some extended exposures at times.
set your aperture to F/22 (reasoning is for long depth of field)
preset your lens focus to 1 foot or 1 meter if 1 foot isn't available.
keep your ISO low. I suggest 100-400 however I never shoot above 200. (reasoning: think of ISO as worker bees. 200 worker bees can capture a picture faster than a 100 worker bees.)
shooting time. this is extremely important because lighting is all part of the feel and emotion of your shot. avoid shooting between the hours of 11am to 3pm as the sun is too high and you'll have harsh shadows. exception to this rule is, in winter time when the sun is lower in the sky, you can shoot mostly throughout the day.. I tried and tested this myself.
set your color to faithful as a fail safe or you can shoot cloudy as it tends to enhance colors but, be careful because the cloudy setting can overdrive color and I'll do a tutorial on how to work with color later.
Use photoshop if you can because my knowledge is due to utilizing post processing with this software and Adobe has a low cost monthly subscription anyway to use photoshop.
Also, don't put the horizon in the middle of the shot. think of this as a war. what are you trying to convey to your viewers; the sky or the land?
Since my health isn't great and my ability to get out and shoot is dependent on my health, the best I can do is pass my knowledge on to others and help everyone.
last piece of advice, the camera doesn't make the photographer, either you have the natural ability or not. also watch your composition. you must have something in the foreground and it should lead the viewers eye to through the shot to the background.
an example is my dear friend Patrick Difruscia and this is his shot. I find him the best darn photographer in my humble opinion.. (credit: Patrick Difrusciaphotography)
Note; he uses all the settings and advice I mentioned above and then some. But you will shoot a perfect shot everytime