There isn't a built-in media library in the portal yet, so the way to share assets with your ambassadors is the Links tab.
Add a custom link that points at wherever your files already live — a Google Drive or Dropbox folder of product photos, a hidden page on your store with your brand guidelines and copy, a Facebook group, or an inspiration board.
Here's how to add custom links. Links open in a new tab and show on desktop and mobile.