<asp:CreateUserWizard ID="createUserWizard" runat="server"
  ContinueDestinationPageUrl="/user/profile/"
  CreateUserButtonText="Continue" RequireEmail="False" ActiveStepIndex="0">
  <WizardSteps>
   <asp:CreateUserWizardStep ID="CreateUserWizardStep1" runat="server" Title="Account details">
	<ContentTemplate>
	 <fieldset>
	  <legend>Account details</legend>

	  <div>
	   <asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">Desired username:</asp:Label>
	   <asp:TextBox ID="UserName" runat="server"></asp:TextBox>
	  </div>
	  <div>
	   <asp:Label ID="PasswordLabel" runat="server" AssociatedControlID="Password">Desired password:</asp:Label>
	   <asp:TextBox ID="Password" runat="server" TextMode="Password"></asp:TextBox>
	   <asp:RequiredFieldValidator ID="PasswordRequiredValidator" runat="server" ControlToValidate="Password"
		Display="Dynamic" EnableClientScript="false" ValidationGroup="createUserWizard">*</asp:RequiredFieldValidator>
	  </div>
	  <div>
	   <asp:Label ID="ConfirmPasswordLabel" runat="server" AssociatedControlID="ConfirmPassword">Confirm password:</asp:Label>
	   <asp:TextBox runat="server" ID="ConfirmPassword" TextMode="Password"></asp:TextBox>
	  </div>
	 </fieldset>

	 <div class="errors">
	  <asp:ValidationSummary runat="server" ID="validationSummary"
	   DisplayMode="BulletList" ValidationGroup="createUserWizard"
	   HeaderText="<b>Please correct the following fields:</b>"
	   ShowMessageBox="False" ShowSummary="true" />

	  <asp:Literal ID="ErrorMessage" runat="server" EnableViewState="false" />
	 </div>
	</ContentTemplate>
   </asp:CreateUserWizardStep>
  </WizardSteps>
 </asp:CreateUserWizard>

protected override void OnInit(EventArgs e)
 {
  base.OnInit(e);

  createUserWizard.CreatedUser += OnUserCreated;
  createUserWizard.CreateUserError += OnError;
  createUserWizard.NextButtonClick += OnNextButtonClick;
 }

 protected void OnUserCreated(object sender, EventArgs e)
 {
  //Add user to group and redirect to destination page.
 }

 private void OnNextButtonClick(object sender, WizardNavigationEventArgs e)
 {
  CreateUserWizard wizard = sender as CreateUserWizard;

  if (wizard.ActiveStepIndex == 0)
  {
   try
   {
	if (Membership.ValidateUser(createUserWizard.UserName, createUserWizard.Password))
	{
	 MembershipUser newUser = Membership.CreateUser(
	  createUserWizard.UserName,
	  createUserWizard.Password);

	 //add user to group and redirect to destination page
	}
   }
   catch (MembershipCreateUserException ex)
   {
	SetFailureMessage(ex.StatusCode);
	e.Cancel = true;
   }
  }
 }

 public void SetFailureMessage(MembershipCreateStatus status)
 {
  switch (status)
  {
   case MembershipCreateStatus.DuplicateUserName:
	createUserWizard.DuplicateUserNameErrorMessage = "Username is not available."; //the string is fetched from a database.
	break;

   case MembershipCreateStatus.InvalidPassword:
	createUserWizard.InvalidPasswordErrorMessage = "Password is not secure enough"; //the string is fetched from a database.
   ...
  }
 }

 private void OnError(object sender, CreateUserErrorEventArgs e)
 {
  if (e.CreateUserError == MembershipCreateStatus.InvalidPassword)
  {
   CreateUserWizard wizard = sender as CreateUserWizard;
   wizard.InvalidPasswordErrorMessage = "Password is not secure enough"; //the string is fetched from a database.
   ...
  }
 }

<asp:Label ID="lblErrorMessage" Text="" runat=server CssClass="failureNotification"></asp:Label>

try
{
    //Do stuff here
}
catch (Exception ex)
{
    lblErrorMessage.Text = string.Format("An error has occurred. Please tell tech support that you saw this: <br />{0}: {1}", ex.GetType(), ex.Message);
    e.Cancel = true;
}