Showing Pictures on a Diagram
There are two stages to this. See Index for related topics.
If you have not yet added any pictures to Family Historian then see the advice on Adding Photographs and Other Multimedia.
Assuming you have pictures attached to your individuals, with a diagram displayed. Select from the Diagram menu, Diagram options and then select the Pictures tab as shown below.
Finally select the Preference Drop down box and set it to 1, to select the first picture attached to the individual.
Also separate text boxes, pictures, shapes, and lines can be inserted into a diagram as explained in Adding Text Boxes to a Diagram.