Using Shopify, how can I grab a customer's address on signup and store it as the default billing and shipping address?

I am creating a shopify site and I am trying to customize it, so when a user / user signs up, they can provide their address information at that time and save it as their default address. Shopify currently has it, so you sign up and then go to the account page where you have the option to add an address.

I've tried creating form elements on the registration page that works the way the data appears and receives in them. But I don't know how to make a form to send the address data to the default data addresses. In other words, I don't know how to store the address as the default address.

I went through the code for the actual address page and tried the plugin in id names and forms in the registration section with no luck. I have tried using the ids and names associated with the client api link and no luck. I can't find any documentation on this. There is a section on capturing additional information during registration, but capturing it as "Notes" not as an address.

Any help would be greatly appreciated.