Image size must be 640×427 to work in the slider.
To change slider options, click “Adv. Slider” menu in the dashboard. To add slider items, create a new post in category “Homepage Slider”. Make image you want to include the “Featured image” of the post. Title of post will go onto overlay, text of post will also be overlaid.
To have image link to a specific page, make a custom field on the page “advps_custom_link”, the value of this field should be set to the URL.