To adjust the transparency of a background color of your Website Builder, please follow these steps:

1. Sign in to your Dynadot account.
2. Select “My Websites” from the left-side menu bar.
3. Click on the "edit" link next to the website builder you want to use.
4. Click on the "Design" icon on the left-hand tool bar.
5. Click on the circle next to the "Background" color you want to adjust.
6. Select the color you want, then use the slide bar to adjust the transparency.
7. Click "Save" at the top to save your changes.

Learn how to change the background color of different sections of your website. You can also set the same background for your entire page or how to remove your background completely.