Hello, Homepage carousel shows the blog post of your theme that contain image. Create a post with an image, it will automatically display at your home page.
You have to click the 'Set Featured Image' link on the right hand side when editing a post. It showed then for me.
Hello, This issue maybe because of plugin (if installed). So please deactivate all plugins to see if this resolves the problem? If this works, re-activate the plugins one by one until you find the problematic plugin(s). Thanks & Regards Gourav Shrivastava