Make a deviation (maybe a wallpaper) with pretty big resolution and upload it do deviantART, you can say an A3 size. Then after uploading and submitting it, deviantART's automated system will ask you if you wanna make your deviation as a print.
Oh hey again, thanks a lot for the info. So suppose if I wanted to make one of my current walls into a print i would have to upload a new one to make it a print ?, and what resolution would you say would be okay for it ? for ex : 2560x1600.