...
Name the Form.
The right section called Your Contact Form displays the fields that are already in your Contact Form. (Every Contact Form has a set of default fields which are added automatically. Those that you can remove have an symbol next to them, as shown in the image below. The name field is now removeable, to know more about it, go to Remove default name field)
...
You can add existing fields to your Contact Form and/or create new fields to add to the Contact Form.
To add existing fields: Search your library of fields to find fields to add to your form:
Use the Search bar in the Find a field section to look for a specific field.
Do not press Enter; instead simply type the field into the search bar and wait for the search results to appear.
Press the green Add to Form button to add the field to your Contact Form
Use the Field Filters to filter the type(s) of fields that appear in the search results
...