To use any of these images as your desktop background you will need to do the following:

Windows Computer : Click on one of the thumbnails below and a full size version of the image will appear in a new browser window. What happens next depends on the browser you are using; with Internet Explore and Firefox you can right click the large image and you'll see an option to 'Set as background' or similar, select that and you are done. With Chrome you don't get a similar right click option so you will have to save the image (you can do this with IE and Firefox too if you wish) then find it using Windows Explorer where you will find that, if you right click on it, you can select the option 'Set as desktop background'. Of course there are lots of other ways to change your desktop appearance in Windows, right click the desktop and select personalise and you'll soon get the idea!
Apple Computer: It's very similar to the process with Windows but I understand (I don't have an Apple computer!) that you should replace right click with Control + Click to get the option. 
The images are 1920 x 1080 so are optimised to display well on widescreen monitors.

Want them all? Click Here to download a zip file containing all 30 images!