Unable to add extra fields to the Registration form in my ASP.NET 4.5 web application

I'm building ASP.NET 4.5 web application and have been trying to add additional fields such as firstname, surname, DOB, etc using Profile but need help with the last part which is to save the data entered for the extra fields when the user presses Register (on Register.aspx page).
Below is the Profile section in the Web.config:
<profile defaultProvider="DefaultProfileProvider"> <providers> <add name="orp_v1ConnectionString" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" /> </providers> <properties> <add name="Firstname" type="String"/> <add name="Surname" type="String"/> <add nam ...