For displaying images you can use the component only.
If you want to display images in articles, you can use Phoca Gallery Plugin (and Phoca Gallery Button plugin - for easier adding of images into articles).
Images can be displayed as slideshow in articles with help of Phoca Gallery Slideshow plugin or they can be displayed on module positions in Joomla! (with help of Phoca Gallery Image module).
How it looks from visitors: Demonstration
That is available to the administrator of the site (login and password - DEMO): Demonstration