The iPad comes with a default background image for the Home screen (wallpaper picture) as shown on the screenshot - but it also includes 18 other pictures you can use for your Home screen, from other landscape photos, to patterns, and abstract images - and you can change Home screen wallpaper to any of these.
This tutorial will explain how to access the built-in wallpapers (so you can see them without necessarily changing your background picture), and how to change your Home screen's image using either one of the official iPad wallpapers, or any picture you have in your Photos library - this also includes screenshots you may have taken on your iPad! (How to take a screenshot on your iPad.)
Follow these steps to change the background image on your iPad:
Tip: if you have used a Saved Photo as background image, and since then removed the image file from your iPad, it will still remain as background, but no longer be listed under Wallpapers or Saved Photos.
Background Tip # 2: while your iPad will let you use any supported image file type (JPEG, GIF, PNG...) as background image, any animated GIF will be used as a static background: in other words, you cannot have an animated Home screen background picture.
Your iPad will work with pretty much any picture you save to your Photos library and choose to use as background, without much distortions (blurriness due to resize) in most cases; for optimal effect, use a square picture with a height and width of 1024 pixels - this also depends on how you mostly use your iPad, in portrait mode, or rotated in landscape mode: read more about the variable iPad screen resolution (in pixels).
While this is a common request, you cannot yet use a different background image for each Home screen: at this point, you can have two different background pictures, one for the Lock screen, and another for all Home screens.