You might have a look at this link, it may help some.

https://www.wincustomize.com/upload-guidelines

This is a lot more complicated, yet simple than you think.

The wallpaper should be functional. It doesn't matter how pretty, stylish, intricate, artsy, etc. it is. It has to be functional on the desktop. No to busy, distracting, and a host of things.

Then there is the technical side of it. Perspective, lighting, shadows, etc.

Your best bet is to look at what has been accepted.

Just to show you how 'quirky' it can be sometimes...here are three wallpapers I submitted. Only ONE of them made it (after a lot of tweaking of the original). I'll let you figure out which one made it in. (I thought they were all good. So you are not alone in trying to get a grasp on what is acceptable, functional, and technically correct. It's an ongoing lesson.)

Start with something simple and build on and when it looks good and you want to add more to it...STOP.

Use the thread you've been using Wallpapers In Progress for feedback.

I see what you're working on in there and again....start simple.

Photoshop. Nothin hard.

Check out Good Tutorials for tutorials in several different programs (PSP, Bryce, etc)

Thanks I realy apriciate your help for me as a Zbrush artist it is hard to "standout" basically all my work is based on characters but i like WC its not that i must be on the gallery i do it for my personal fun and as long as iam pleased im satisfied...I just thought am im that bad at what iam doing ?
It would be nice to be on the gallery but i can live without it.
My photshop skills are standart i guess i can use it but most of the time im without a plan what i should do as background i made some works and quite a lot tutorials already but i do not know by far all about it. IT only drove me crazy not to know what iam doing wrong but now as u say the wall has to lift off from others i can understand what i might do wrong just trying to get more into the situation of whats nessesary

@k10w3 Thanks i might try that but first i got to finish my project Liberte but maybee i do some icons i would need to take a look on how i create an iconpackage - Zbrush isnt that hard basically it works like Photoshop and like with every tool or Program you start working with, first steps are complicated but Zbrush realy isnt its quite easy... For me it was a pain in the beginning aswell especially because i never had someone that teached me tricks or how to start same in photoshop i basically tryd and worked my way trough there till i understood the tools buttons and so on after that i started making tutorials that others had created and each tutorial is a step further into the world of Zbrush or PS... ^^ if you need any help with Zbrush i will gladly be there if you have any questions ^^
BTW just brought my daughter into bed and had some time so i thought i first say thanks to PoSmedley for helping me understand what it takes to get to a gallery on WC ... and the best way to say thanks is with a little something it might be not 100% accurate and it was quite fastly done but here you go BTW your Avatar reminds me of Tory from the Mythbusters   

its indeed gorgeous and i know that wall...this is what i would like going for ! i could do something similar with liberte but im afraid remodeling the whole body (because of mature content ) would throw me back at least 2 weeks.+ i could never achive that much detail, my PS skills wont allow it.
My issue is the lack of creativity for such a backgound and the very well planed things that complement the entire Structure.
I never know what i should go for... I have made tons of characters in Zbrush but i always end up starting new stuff since i simply cant get a nice wall out of it. So i keep building and building in Zbrush...BTW Organic didnt know Jafo is into Cyborgs and Science Fiction
But as you say its hard to top a masterpiece and you have to be creative yourself and you wont want to copy other Artist work you may try but in the end you will fail by trying its like the trying to paint Mona Lisa.BTW i think he used PS only to achieve that! [ Edit ] : jupp Photoshop and 3Dmax only
But thanks for your Tips i will try not to oversaturate the entire wall i will try o make it decent yet eyecatching...

i can animate them aswell but this takes a little bit more time than sculpting because you have to set waypoints and create diffrent positions of the body part that should move... but the outcome would be a video...but for that i need Maya and sadly i cant afford that atm i would have to ask a freind for a favor