Comment on WordPress Header Images by SEO Dave.
If you had uploaded the images to the custom-01 folder images would be available under that folder.
The image doesn’t load therefore you can’t have confirmed you uploaded the images correctly.
This 100% confirms the correct images are not in the custom-01 folder and your server is working correctly regarding showing images.
You’ve either not uploaded the images to the /wp-content/themes/stallion-seo-theme/landscape/custom-01/ folder or you named your banner images incorrectly.
Make sure they have the correct naming format landscape-1.jpg and they are in the /custom-01/ folder. When you think you have it right check if it loads your first image you got it right, if not try again.
I can’t confirm either of these by logging into your site (the WordPress Dashboard doesn’t list server contents), you will need to use FTP or your control panel to confirm the files are the right names and in the right location.