Right-click the desktop on your Mac and choose Change Desktop Background.
2.
You can now choose from a bunch of built-in desktops. You can also choose how you want the image to appear. If you want it over the whole screen then choose Fill Screen etc.
If you want to add a new location to choose the wallpapers from, click the + (add) button and choose the new location.
4.
To activate or deactivate your Mac's screen saver, click the Screen Saver button.
5.
You can now choose from a bunch of screen savers, try them out and choose which one you like the best. If you want a personal message to appear, the choose the Message screen saver and put in your message.
I chose the Random option, meaning I get a random screen saver every time it activates.
Set after how many minutes after you stop working on the computer should the screen saver start, and if you want to tell the time while looking at the screen saver then enable the Show with clock option.
6.
You can also activate the screen saver using Hot Corners...
