How to Put a Picture on the OS X Yosemite Desktop
You can customize your Desktop in OS X Yosemite by setting your favorite photo as the background. The first figure shows a Desktop with a portrait of a dog, Zeke, painted by talented artist Jeanne Illenye.
(The next figure shows the default Desktop background.)
Here’s how you can change your Desktop picture:
From the Desktop, choose Apple→System Preferences.
Or right- or Control-click the Desktop, choose Change Desktop Background from the contextual menu, and skip to Step 3.
The System Preferences window appears.
Click the Desktop & Screen Saver icon.
When the Desktop & Screen Saver pane appears, click the Desktop tab (if it’s not selected already).
Click a folder in the column on the left and then click a picture in the area on the right.
A picture called Elephant is one of the items in the Desktop Pictures folder.
You have at least three other ways to change your Desktop picture:
Drag a picture file from the Finder onto the image well (the little rectangular picture to the left of the picture’s name).
Click the Desktop tab in the Desktop & Screen Saver System Preferences pane and then click the + button at the bottom of the list on the left. Choose a folder in the standard Open File sheet and that folder appears in the list; you can use any picture files it contains for your Desktop picture.
Click the iPhoto (or Aperture) item in the column on the left side of the Desktop & Screen Saver preference pane and choose from pictures stored in iPhoto or Aperture.
Apple sounded the death knell for iPhoto and Aperture in early 2014. A new app called Photos will replace both sometime in 2015.