N.B. The screenshots and descriptions are for the iPhone/iPad version.

Galleries allow you to store photos and videos of a horse together in logical groups such as years or events.
To add a gallery, go to the Gallery Icon on the horse's home screen and tap on the '+' icon at the top right of the screen and add your title, e.g. '7 Years Old' or 'Villamoura, Autumn 2021'. You can optionally add a description.
Once you have saved your gallery, if you touch and hold it you can either edit the title and description or delete it.
To add a media item, tap on the gallery you have created, then tap on the '+' icon at the top right of the screen. You can then select and upload a media item from your device or any cloud storage it is connected to. You can also add an optional caption. The media file will be uploaded to the server so that it can be accessed by your other devices and other app users' devices.
If you tap on an image you can see an enlarged view. To zoom in on a particular part of the image, you can double tap then hold and drag to move around.
To share the image tap the icon at the top left of the screen, then select a recipient.
If you touch and hold an item in the gallery screen, you will see a menu allowing you to delete the media item or apply/edit a caption.
One of the menu options allows you to select that image as the profile picture for that horse. If there is one selected and you select a different one, it will automatically be replaced. You can alternatively clear it as a profile picture and none will be displayed.