@aruraza: I see that you are using Catch Evolution Free Theme and only have option to user Featured Post Slider to highlight your post. So, first you need to create post and add in featured image in your post. Then get the post ID and add the IDs in “Appearance => Theme Options => Featured Post Slider”.
For more, check our theme instructions page at http://catchthemes.com/theme-instructions/catch-evolution/ and read “Image Sizes”, “How to add Featured Image in Post/Page?” and “How to Add Featured Post Slider?”
You can also check out Catch Evolution Pro theme where you have option to use “Featured Image Slider or Featured Page Slider or Featured Category Slider or Featured Image Slider”. It also have lot of other additional features. Read the theme instructions page at http://catchthemes.com/theme-instructions/catch-evolution-pro/