[Required(ErrorMessageResourceName = "ValidationErrorRequiredRole", ErrorMessageResourceType = typeof(ValidationErrorResources))]
[Display(Order=7, Name="RoleName", ResourceType = typeof (RegistrationDataResources))]
public string RoleUser { get; set; }

Roles.AddUserToRole(user.UserName, user.RoleUser);

   public IEnumerable<User> GetUsers()
        {
            var usersDB = System.Web.Security.Membership.GetAllUsers();
            List<User> users = new List<User>();
            foreach (MembershipUser user in usersDB)
            {
                var tempUser = new User();
                tempUser.Name = user.UserName;
                 users.Add(tempUser);
            }
            return users;
        }

<Grid x:Name="LayoutRoot">
<riaControls:DomainDataSource AutoLoad="True" LoadedData="userDomainDataSource_LoadedData_1" Name="userDomainDataSource"
 QueryName="GetUsersQuery" >
   <riaControls:DomainDataSource.DomainContext>
      <my:UserRegistrationContext />
    </riaControls:DomainDataSource.DomainContext>
   </riaControls:DomainDataSource>
  <sdk:DataGrid AutoGenerateColumns="False" Height="200"  ItemsSource="{Binding ElementName=userDomainDataSource, Path=Data}" 
Margin="185,116,0,0" Name="userDataGrid" RowDetailsVisibilityMode="VisibleWhenSelected" VerticalAlignment="Top" Width="400">
      <sdk:DataGrid.Columns>
                <sdk:DataGridTextColumn x:Name="nameColumn" Binding="{Binding Path=Name, Mode=OneWay}" Header="Name"
 IsReadOnly="True" Width="SizeToHeader" />
      </sdk:DataGrid.Columns>
     </sdk:DataGrid>
    </Grid>

<profile defaultProvider="AspNetSqlProfileProvider">
      <providers>
        <clear />
        <add name="SqlProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices"
 applicationName="SampleApplication" description="SqlProfileProvider for SampleApplication" />
        <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" 
applicationName="/" />
      </providers>
      <properties>
        <add name="UserId" type="System.Guid"/>
        <add name="FirstName" type="String" customProviderData="FirstName;varchar;50" />
        <add name="LastName" type="String" customProviderData="LastName;varchar;50" />
        <add name="FriendlyName" type="String" customProviderData="FriendlyName;varchar;50" />
        <add name="PhoneNumber"  type="String" customProviderData="FirstName;varchar;50" />
      </properties>
    </profile>

[DataMember]
        public System.Guid UserId { get; set; }

        [DataMember]
        public String FirstName { get; set; }

        [DataMember]
        public String LastName { get; set; }
             
        [DataMember]
        public string PhoneNumber { get; set; }

        [DataMember]
        public string FriendlyName { get; set; }

ProfileBase proff = ProfileBase.Create(HttpContext.Current.User.Identity.Name);
//Или
//ProfileBase proff = ProfileBase.Create(this.ServiceContext.User.Identity.Name);

proff.SetPropertyValue("<имя поля например LastName > ", "значение");
proff.Save();

ProfileBase proff = ProfileBase.Create(HttpContext.Current.User.Identity.Name);
//Или
//ProfileBase proff = ProfileBase.Create(this.ServiceContext.User.Identity.Name);

var Last = proff.GetPropertyValue("<имя поля например: LastName > ");

ProfileBase proff = ProfileBase.Create(HttpContext.Current.User.Identity.Name);
//для записи в профиль пользователя
proff.SetPropertyValue("<имя поля например LastName > ", "значение");
proff.Save();
//и для чтения 
var valueProf =proff.GetPropertyValue("<им свойства профиля>");

WebContext.Current.User.FirstName = "asadad";
WebContext.Current.Authentication.SaveUser(false);
 string str = WebContext.Current.User.FirstName;