How To Change Wallpaper On A Emachines Mini Laptop?

"I'm presuming it's Windows 7 Starter Edition. Starter is especially made for netbooks, so it doesn't use up as much power and you can get a nice, fast netbook experience (Comes with less features and personalization)
If you can, you could upgrade to Home Premium but it would probably slow down (not enough processing power in netbooks)
To upgrade to Home Premium, go to "Windows anytime upgrade"
Good luck!"

Right click on any blank area of the desktop,
A box will appear listing several command, you want to select "properties"
Another tabbed dialog box will open.
Select the "Desktop" tab.
You will see a mini-image of you current desktop and below it, choices of other desktop images which you can choose from. You can also use the "Browse" button to look in other locations for files such as .bmp, .jpg that you can use for desktop images.
Make your selection, click the "Apply" button and then "close"
That's all there is to it.