It's very easy to transfer your wallpaper to your iPad. First, choose one of the images to the right and download the .jpg file to your desktop. Open iTunes and use the Add to Library function [File/Add to Library] and pick out your JPG. iTunes cleverly knows to add it to your photos on your iPad.
To put it to use, plug your iPad into your computer so it can sync the Photo Library. Then use the Settings app on the iPad and pick Brightness & Wallpaper. From there you’ll be able to pick from all the photos on your iPad. Find the JPG you added to iTunes in your Photo Library.
You can use your wallpaper for either the home screen (behind your app icons), or for your lock screen (the one that comes up when you wake up the iPad). Or both, your choice.