This article applies to the Website V3.
While it is not possible to edit the entire HTML source for site created with Vistaprint's Sitebuilder, you can add custom HTML snippets to your page:
Click the Other tab at the bottom of the Builder.
Select the Custom HTML module and drag it onto the page.
Once the placeholder appears, double-click to paste your HTML code.
The code will not render in Builder mode. To see how the finished product will look on your website, click Preview at the top of the Builder.
IMPORTANT: You are responsible for troubleshooting any custom or third-party coding that you add to your site.