Hello Janice,
Thank you for your question about adding a contact form and a calendar in the Premium Website Builder. Yes, you can add HTML code in the builder by using the Scripts Module in Step 4 - Edit. However, to add a contact form, you can simply use the Feedback Module (also in Step 4).
While the builder does not have a built-in calendar module, you could add a calendar to your website and then integrate that third party software into your Premium Website Builder site with either an iframe or an External Link.
Please let us know if you have any questions or need further assistance.
Regards,
Christi N.