Adding Post Thumbnail or Featured Image in WordPress
To add a featured image in a WordPress post, simply edit or create a new blog post.
In the content editor, you’ll find the featured image tab in the right column.
You need to click on the ‘Set Featured Image’ area, and this will bring up the WordPress media uploader popup.
From here, you can upload an image from your computer or use an existing image from your media library. Once you select the image, simply click on the Set Featured Image button.
WordPress will now show a preview of the featured image in the right column. However, the actual featured image would look different depending on your WordPress theme.
You can now save or publish your post and preview it to see how the featured image will appear on your live website.
Depending on settings defined by your theme developer, your featured image will automatically appear with your posts.