Please refer to mac basic faqs: how to change your Mac OS X desktop if you wish to change your Mac OS X desktop.

To Change Your Screen Saver

1. From the Apple menu, choose System Preferences to open the System Preferences window.
2. Click the Desktop & Screen Saver button to display its preferences.
3. Click the Screen Saver tab to display just the Screen Saver preferences. All installed screen savers appear in the left pane. The right pane displays a preview of the selected screen saver.
4. Click one of the Screen Saver items in the left pane to select it for use.
5. If you’d like, click Test to see what the screen saver will look like in use.

To create a slideshow screen saver, do one of the following:

1. In the Screen Saver preferences window, select Library or one of the two choices below it to turn your iPhoto images into a slideshow screen saver.
2. In the Screen Saver preferences window, select Pictures Folder to display the images in it, or select Choose Folder, navigate to and select a folder that contains images in the resulting dialog, then click Choose to put it in use.

To add a third-party screen saver:

1. If the screen saver doesn’t have an installer to place the file in the right folder, locate the .saver file in the package.
2. Drag the file into the Screen Savers folder, which is in the Library folder at the root of your hard disk ~/Library/Screen Savers.
3. Follow the steps in “swap your current screen saver for another one,” above, to select the third-party screen saver.

Customize Your Screen Saver
Now that you’ve outfitted your Mac with a new screen saver, you can further customize its settings. Here are some of the things you can do in the Screen Saver preferences window.

1. Click Options to view the selected screen saver’s user-configurable display settings and adjust them to your liking. These settings will vary screen saver to screen saver.
2. Move the “Start screen saver” slider left or right to change the time, in minutes, at which the screen saver begins to play.
3. If you’d like the ability to start the screen saver manually, click Hot Corners. In the resulting dialog, choose Start Screen Saver from any of the four corner pop-up menus and click OK. The screen saver will start when you move your arrow to your chosen screen corner.
4. If you’re the adventurous type, select “Use random screen saver,” and your Mac will automatically select a screen saver when it goes into screen saver mode.

1. From the Apple menu, choose System Preferences to open the System Preferences window.
2. Click the Desktop & Screen Saver button.
3. Click the Desktop tab; the left pane lists the different folders from which you can choose an image. The right pane displays thumbnails, small images, of the images in the selected folder.
4. Click Apple Images to select it. You’ll see the default picture in the right pane, along with a bunch of other images.
5. Click any thumbnail to instantly change the desktop image. Feel free to click a few different ones to try them out.
6. Now select Nature in the left pane. Then click any of its thumbnails to place a nature type picture on your desktop. Do the same for Abstract.
7. If you’d rather have a solid color desktop, select Solid Colors in the left pane, and select a color swatch from the right pane.
8. When satisfied with your choice, close the Preferences window.

Of course, you can turn any of your own photos or artwork into a desktop picture too. Here’s how to do this:

1. From the Apple menu, choose System Preferences.
2. In the window, click Desktop & Screen Saver, then click the Desktop tab to display just the desktop preferences.
3. If you want to use a photo from your iPhoto Library, select Library in the left pane. Otherwise, select Choose Folder, navigate to and select the folder that contains your image, and click Choose.
4. In the right pane, click any thumbnail to place the image on the desktop.
5. Depending on the size of your chosen image, you can opt to tile or center it if it’s small. Note: Your image will look pixelated or have jagged edges if it’s too small. Or have the image fill the screen, or stretch to fill the screen. Just choose an item from the pop-up menu that appears above the thumbnails, the one next to the thumbnail of your current picture.

You can also have your Mac automatically change your desktop picture. To do this:

1. Select the “Change picture” checkbox. Note: This option is not available if you selected your iPhoto Library or an iPhoto picture roll.
2. From the Change picture pop-up menu, choose one of the intervals listed in the menu (such as every minute or every day—or choose every 5 seconds for a desktop slideshow).
3. Select the “Random order” checkbox if you want the images to appear at random. If it isn’t selected, your images will appear in alphabetical order by name.