Formidable Forms Date Picker Calendar

Hi
Good morning.
I wish everyone is in good health and happiness.
There is an existing form at https://honyakuservices.com/get-a-quote/

But I wanted to change the form with an updated one.

Insert a Calendar Date Picker etc.
I have a HTML long code for the design.

Will someone help me to how to insert my HTML code for the design in this Formidable Forms step by step.

The page I need help with: [log in to see the link]