This is a two step process:
- Add a CCK Image field to Page content type
- Add a CCK image field named "header_image", machine readable name is "field_header_image"
- Type->File and Widget->Image
- Go to Display Fields Check Excude for both Teaser and Full node (We don't want to have default durpal render, we will add it in a separate block below)

- Add the following line to page.tpl.php file, immediately after the page content starts.. Usually immediately after the wrapper div based on your theme.
<div class="banner"><?php print $node->field_header_image[0]['view']; ?></div>
- Now create a page content and upload the banner image, it should show it on the page at the top
Make sure this field name matches the one you created. Use CSS to style banner div. This is tested for both Drupal 5 and Drupal 6.x.

Comments
thanks!
totally answered my noob question. thank you!