On a side note, i forget if underscores are allowed in names or not. If the above doesnt work, try taking the undescores out and saving the page again in the panel.
My apologies if the question is difficult to understand. I will try to make it understandable.
Think of an image about_us.png, that contains the photo of our team. Just that image, how does one create a panel where Admin can upload this image so that it is displayed on the about page in location where I want it to be.
Not an album. All examples I saw were related to Albums.
Normally I would have a content folder /about/ with the image about_us.png and use <?php echo $page->image('about_us.png')->url() ?> to display it on the page.
How do I create a panel component to change that image and what do I put in the blueprint?
You dont need a file blueprint unless you want to store meta data or limit what type of files can be uploaded. The purpose is to keep your page blueprints clean
Is there a faster way to do this? Or do I need to PHP to file every time for an image? Before I could just do <?php echo $page->image('header.jpg')->url() ?>
You could do that but it is not recommended coding style. If you simplify your code like in your above example, it means that it will throw an error if the file doesn‘t exist.