Customise the desktop picture on your Mac
You can change the picture that’s displayed on your desktop. Choose from a variety of pictures or colours provided by Apple, or use your own photos.
Tip: You can drag an image from your desktop or a folder onto the thumbnail at the top of the pane to use the image as your desktop picture.
On your Mac, choose Apple menu
, then click Desktop.On the left, browse available pictures and colours:
Pictures and colours from Apple: Click the arrow
next to Apple, then select a folder. To download a picture (indicated by the download icon 
), you must be connected to the internet.Dynamic and Light and Dark desktop pictures automatically change throughout the course of the day based on your current location. If Location Services is turned off in Privacy preferences, the picture changes based on the time zone specified in Date & Time preferences.
Some pictures provide still images so the picture doesn’t distract from the desktop appearance. For example, if you chose the dark appearance during macOS setup, the desktop picture is set to a dark still image. To use or stop using a still image (if available), click the pop-up menu next to the thumbnail at the top of the pane, then choose an option.
Your photos: Click the arrow
next to Photos. If your photos are in the Pictures or another folder, click the arrow next to Folders, then select a folder.To add a folder, click the Add button
, navigate to and select the folder, then click Choose.If your photos aren’t shown, they might not be in the expected file format — JPEG, PICT, TIFF, PNG or HEIC. Use Preview to open your photos and save them in one of the formats. If your photos are shown but look fuzzy, try using larger ones, such as 1024x768 pixels.
On the right, click a picture (if the picture has a download icon, click the icon) or photo to use it as your desktop picture. Try different ones until you find the one you like best.
If you decide not to use a downloaded picture and want to delete it from your Mac, Control-click the picture, then choose Remove Download.
If you use one of your photos, you can choose to have it fill the screen, be centred or otherwise arranged.
For some folders, you can show all the pictures in the folder. Select “Change picture”, then choose how often to change it, such as every hour. The pictures are shown based on their order in the folder, or you can choose to show them in a random order.
To quickly use a photo you have in the Photos app, open Photos, select the photo, click the Share button 
in the Photos toolbar, then choose Set Desktop Picture.
You can use a picture you find on the web as your desktop picture. Control-click the image in the browser window, then select Use Image as Desktop Picture.