Add photos to your Photos project for Mac

After you create a project in Photos, like a book or a slideshow, you can add more photos to it with a simple drag and drop from the sidebar.

First, make sure the sidebar is visible on the left-hand side of Photos. You can do this in two ways:

• From the View menu, choose Show Sidebar. 
• Or, Press Command-Option-S.

With the sidebar visible, you can see all your albums and projects. Here's how to add photos to a project:

1. Select an album in the sidebar. You can select one that you've created, or you can use the All Photos album.
2. Select the photos that you want to add to a project. To select multiple photos, hold down the Command key as you click.
3. Drag the selected photos to the sidebar and drop them on the project you want to add them to.