Images in a WP site are either loaded through the theme code (wp-content/themes/name-of-your-active-theme), or via the back-end in a post or page.
Based on the link you provided, which links to uploads, that particular image was linked in the backend. And that is where you will need to change the link: insert an image, and choose "insert from URL".
If you need the site's behaviour/look to be adjusted, you must edit the active theme files. Based on your question, I assume you have no prior experience with WP theme development (or editing). VBA will not help you here: you will need basic PHP knowledge and a reasonable understanding of how WP themes work and are structured, including basic WP PHP functions. Without these foundations, you are groping in the dark.
Learn more about WP theme development on the official WP Codex documentation site:
Theme Development « WordPress Codex
As for using Dreamweaver to edit a WP site: the only thing you should be working with are the theme files. Do not create a DW project/site based on the entire WP installation folder. Only point DW to the active theme folder you are editing.
Lastly, to develop or edit themes ideally requires a LAMP stack such as XAMPP, WAMP, or MAMP installed on your machine. Simple changes can be made by editing the online theme files, but you risk losing those changes when an update for that particular theme is released, which will overwrite the edits you made. Which means you will at the very least have to create a child theme based on the original to prevent this from happening.