@helenage: Catch Everest free theme only have Featured Post Slider. But you will get more option in Pro version.
Here goes the instruction to add the Featured Post Slider
1. First create the Post and don’t forget to add in the Featured Image in the post as this image is used in the slider. To add featured image see this http://en.support.wordpress.com/featured-images/#setting-a-featured-image
2. Then get the ID of the post. When you edit your post or write a post, you will see the id in your browser address bar. You will also be able to get the post ID from All Post in your WordPress Dashboard. But still if you cannot find it then you can use this plugin to view it http://wordpress.org/extend/plugins/catch-ids/
3. Then go to “Appearance => Theme Options => Featured Post Slider => Featured Post Slider Options”. Add in the post id. Make sure you only add in the ID number.
For other question. Yes thanks to @NyaKungen: The three small images is called Homepage Featured Content. Which you can change it from “Appearance => Theme Options => Homepage Settings => Homepage Featured Content Options”.
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