depending on what operating system you have its slightly different.
on windows XP: right click desk top - properties - [select the] desktop tab: you can then either select 1 of the many built in ones or press 'browse' and use your own.
on windows 7 and vista its: right click desk top - personalise - [from here you can select a built in 1 that comes with the operating system ] - desktop background [located at bottom of new window] - and select brouse to locate 1 of your own.
I'm sorry, but I think you have the newer EEE pC's, don't you? The versions with Windows 7 Starter does NOT allow the user to customize the background of the OS. Of course, there are workarounds this.
Try looking for Starter Wallpaper Changer, Oceanis Background Changer, or Wallpaper Changer for Windows 7. This will allow you to change your background on the netbook.
Hope this helps you, if it's what you were looking for.
nothing... i think i should go back to best buy and ask maybe? gah theres nothing i searched EVERYTHING in my computer... nnothing to change the background ):<
im sorry but are you using wndows 3 or summet? :S what operating system are you using?