When a user is logged in, you can access details about the user using ASP.NET code. Here are a few simple examples to demonstrate that.
Sample ASCX File:
<%@ Control Language="c#" Inherits="Waypoint.Core.WPControl" %>
<%
//IF AUTHENTICATED, THE USER OBJECT WILL NOT BE NULL
if(((Waypoint.Core.WPPageLite)Page).AuthenticatedUser!=null){
%>
Hello <%= ((Waypoint.Core.WPPageLite)Page).AuthenticatedUser.First_Name %>.
<%
}
%>