As an administrator of a organisation you can publish a picture album to your organisation's public page.
Under your organisation click "Pictures".
Select album
On this page you will be shown all the picture albums that belong to your organisation. Select the album you want by clicking it.
Publish
By clicking on the "Public" button the selected album will be published to the organisation's public page.
Afterwards, the button "Public" will change to "Not public". You can hide the picture album from the public page by selecting this.
Note: Remember that your organisation must have a public page for you to do this. You can find the guide here:
Publish your organisation to the Internet