From the Client List page, click on the Pictures button in the far right column on your screen. (See image below.)
You will be redirected and able to view all of your clients photos that either you (the personal trainer) or the client (if you gave them permission) has uploaded. If you would like to add a new photo, click Add Picture button in the top right portion of the screen. (See image below.)
Next, choose a file, a date, and a caption to add to the photo. When this information is filled in, click Add Image.