We use Getform.io to create the default contact form. Please create an account on getform.io and create a new form by click on the create button and after that getform.io will generate for you a HTML code of the contact form.
You will get this code after click the create button:
You can go ahead and paste these code into the custom-page-with-getform.hbs file and add the class="contact-form" to the form tag and your contact form is ready to go.
But your contact form will look really simple, you will need to restyle your contact form for it to look better
Before restyle
Before restyle
After restyle
You can check on how to restyle your contact form below: