how to write endpoint for web api

I have a project i need to write an endpoint for in asp.net web api. Here is my custom class. Im new to asp.net and i need help on this urgently. Thanks

  public class express
{

    public string firstname { get; set; }
    public string lastname { get; set; }
    public string middlename { get; set; }
    public string dateOfBirth { get; set; }
    public string identityType { get; set; }
    public string email { get; set; }
    public string mobileNo { get; set; }
    public string gender { get; set; }
    public string street { get; set; }
    public string city { get; set; }
    public string state { get; set; }
     }
    }