How to Change the Desktop Background in Mac OS X Snow Leopard
Mac OS X Snow Leopard lets you customize your desktop. If you do decide to spruce up your background, you can select one of the default Mac OS X background images, choose a solid color, or specify your own image. All three backgrounds are chosen from the Desktop & Screen Saver pane, located within System Preferences.
To choose a background from one of the collections provided by Apple, click one of these groups from the list at the left:
Desktop Pictures: These default backgrounds range from simple patterns to somewhat strange and ethereal flux shapes.
Nature: These backgrounds feature scenic beauty.
Plants: Close-up backgrounds of plant life.
Black & White: Several truly stunning black-and-white backgrounds that look especially good on a widescreen display.
Abstract: These backgrounds have even weirder twisting shapes in flux, this time with bright contrasting colors.
Solid Colors: This is for those who desire a soothing solid shade.
Pictures Folder: This displays the images saved in the active user's Pictures folder.
Choose Folder: You can open a folder containing images and display them instead
If you see something you like, click the thumbnail, and Mac OS X displays it in the well and automatically refreshes your background so that you can see what it looks like.
Mac OS X automatically manipulates how the background appears on your Desktop. If an image doesn’t conform to your screen resolution, click the pop-up menu next to the well and you can choose to
Tile the background: This repeats the image to cover the Desktop. (This is usually done with pattern images to produce a smooth, creamy, seamless look.)
Fill the screen: This can be used with a solid color to get uniform coverage. The original aspect ratio of the image is preserved, so it’s not stretched.
Stretch the background to fit the Desktop: If your Desktop image is smaller than the Desktop acreage, this works, but be warned: If you try to stretch too small of an image over too large a Desktop, the pixilated result can be pretty frightening. The original aspect ratio of the image isn’t preserved, so you might end up with results that look like the funhouse mirrors at a carnival.
Center the image on the Desktop: This is a good solution for Desktop images that are smaller than your resolution.
Note that this pop-up menu appears only if the Desktop picture that you select isn’t one of the standard Apple images. All the pictures in the Apple Desktop Pictures, Nature, Abstract, and Solid Colors categories are scaled automatically to the size of your screen.
To change your Desktop background on a regular basis, select the Change Picture check box and then choose the delay period from the corresponding pop-up menu. To display the images in random order, select the Random Order check box; otherwise, Mac OS X displays them in the order that they appear in the folder.