In order to add a Personal Photo (the little photo that appears for a person in the tree), please take the following steps:
1. Click either on the small Camera icon on the Person Card or on the ‘Add photo’ button under the silhouette on the left panel that shows up when you click on the Person Card.
2. Use "Drag a photo here" option to add a new photo or click on ‘Select File’ to choose a photo from a specific file location.
Click ‘OK’ to save your changes.
3. You can also click on ‘View profile’ on the left side to open person’s profile page, and click on ‘Add photo’ under the person’s silhouette.