Open the editor of the post or page where you want to display a unique custom header image, and locate the Featured Image module on the left.  Click Set Featured Image.

You will see an uploading screen identical to that used when inserting an image into a blog post. Follow the on-screen prompts to choose the image from your computer and upload it or choose it from one of the images already in your Media Library.

Once the image has successfully been uploaded, you’ll see one or more images displayed as thumbnails. Click on the one you want to use as a featured image. It will then appear outlined in blue with a check mark. If desired, you can add a caption and alt text under the Attachment Details area (optional).

Next, click the button Set Featured Image at the bottom right:

Don’t forget to click Update on your post/page to save your changes. Your featured image is now set!

To remove or change a featured image, simply re-open the post or page editor and click the Remove featured image in the Featured Image module.