It refers to computers that are stationary and not portable. AKA one that "sits on your desk" versus a laptop which can "sit on your lap" and is portable. Desktops are bigger in physical size and have multiple components to them such as a montior, keyboard, mouse, speakers, and computer tower. In a laptop, these are built into one piece.
what do mean by computer desktop
do you mean a computer please edit your question and elaborate on "desktop"
What do you mean?
The phrase a wallpaper on your desktop can mean that your desktop is covered in papers. This can be meant on your computer or your actual desk.
if you mean background picture for your desktop, right click on you desktop, go to properties then go to Desktop in properties then browe for a picture and click apply
Honestly it depends on what you mean. If your referring to a desktop computer then there is not a way to purchase one for your actual car.
Open the System Preferences - this can be found on the Dock, or in Finder > Applications > System Preferences.Then click on Desktop & Screensavers.You can edit your wallpaper in the Desktop section.
Assuming you mean the "Show Desktop" button, you right click the start back and click "Properties" then check "Show Quick Launch".
It depends on what you mean by old. An old Dell desktop from way back in 2011 can probably be easily overclocked, but a recent Dell desktop from 2004 might be impossible to overclock.
A desktop processor is a processor that has been optimized for maximum performance on the desktop, for tasks such as playing video games or editing video. This is as opposed to a laptop / mobile processor, which is optimized to provide longer battery life and run cooler.
Export: means To Move out of I-Tunes to like a file on you desktop
I am not very sure what you mean by that...but if you mean background as in your wallpaper on your desktop, you can use a picture file that you have or you can even draw your own picture if you have any drawing thing like "Paint", save it, and save it on your desktop. :) Hope this helped.