There
are many versions of the RMTSC desktop picture to suit your needs. For the
jpegs, all you need to do is click on the link. Then, once the picture
loads you can use your browser's "set as wallpaper" function -
available by right clicking (PC) or clicking-and-holding (Mac). To use the
photoshop files (these have the full color image data for you purists),
you should use your browser's "save link as" or "save
target as" function - also available by a right click/click-and-hold.
You will then need to re-save these in another format (BMP for PC, PICT
for Mac) and set this image as your wallpaper.