@katyaY: I see that you are using Catch Everest Free theme. So, please check in theme instructions page http://catchthemes.com/theme-instructions/catch-everest/ for more details
1. Slider: Catch Everest Free theme only have option to use Featured Post Slider to highlight your post. So, first you need to create Post from “Add New => Posts” and in your post, you need to add in Featured Image as this image will be used as image for slider. Then you can go to “Appearance => Theme Options => Featured Post Slider => Slider Options” and add in your post ID. See the detail instruction at http://catchthemes.com/theme-instructions/catch-everest/
2. Homepage Featured Content Options: The 3 boxed and images. You can add link, upload images, title and text from “Appearance => Theme Options => Homepage Settings => Homepage Featured Content Options”.
3. Background: I see that you have added custom background from “Appearance => Background”
If you want more features then you can opt for Catch Everest Pro theme. See the details about additional features and theme instructions of pro version at http://catchthemes.com/theme-instructions/catch-everest-pro/
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