You need to make sure your site is defined properly: Site/Manage Sites or Site/New and define it if it isn't defined yet.

I don't think your graphic is uploaded to the web server. You have spaces in the files name, which I would not recommend. The problem is it is not finding your updated address header.jpg (notice the spaces)

This looks like it is because you have not defined a site for this website.

Jim

This page is not a child page spawned from a DW template, so any legit HTML & CSS code should be editable in DW.

It was apparently created in this software

<meta name="Generator" content="Incomedia WebSite X5 Evolution 8.0.16 - www.websitex5.com" />

If your image is viewable in a browser,  there is no need to go back to your graphics program.

This is a simple link path problem - find the image, rename it without spaces, place it in your images folder and correct the path in your pages' links.

Perfect time to learn SSI (server Side Includes). R E A L L Y  E A S Y

and IMHO, even better than DW templates.

Look it up to grasp the concept

Verify that your hosting supports PHP code (nearly all do) then all you have to do is

copy just the HTML code that you wrote to display your header,

paste it in a text file and save it as header.inc

at the location in the page where you copied the header code,

replace the previously copied code with this bit of code:

<?php require_once("header.inc"); ?>

Repeat for all pages where you want the header to appear

Change your page file names from blabla.htm to blabla.php

Upload the header.inc file and your pages to the server.

If a change is ever needed, you need only modify the header.inc file and upload that one file

and the change will instantly appear in all pages  on the server

If you need any clarification, call me a  9 1 4 - 9 4 1 - 3 6 1 6

Please call me