Windows Users: Right-click on the image and select "Set as
Mac Users: Click and hold your mouse over the photo you
want. A menu will pop up. Choose "Save This Image As," and save it to
Open the image in any image-editing program. Choose "Select All,"
then choose "Copy" from the edit menu.
Next go under the apple menu and select "Control Panels," then
"Desktop Patterns." Go under the Edit menu and choose "Paste." Hit the
"Set Desktop Pattern" button.