How to pass customer details to ActiveCampaign, using a form in ASP.NET web project

I am developing a web project for Tour Management using ASP.NET. In there, there I have a customer registration form. I need to automatically send them emails when the date of the tour is changed. I got to know that it will be easy if I used ActiveCampaign. So I would like to know how to pass my ASP.NET customer registration form data to the ActiveCampaign. In my ASP.NET form there are entities like Customer Name, Address, Email, Mobile…….. etc

Please help me to achieve that goal.

Note that I am a beginner to Active Campaign.

Thank You