Security :: Combining A Captcha With A CreateUserWizard Control?

I have a working registration page and I'm adding CAPTCHA. The CAPTCHA works and I have a simple if/else loop to do what happens if the CAPTCHA input was correct or incorrect.

if (Page.IsValid)
{
feedback.InnerHtml = "Correct.";
//I would like to put something here to process the registration -- CAPTCHA was done correctly
}
else
{
feedback.InnerHtml = "Incorrect.";
}

I want to write something in the if/else loop that will enact the registration.

Therefore, my button in CustomNavigationTemplate,

<CustomNavigationTemplate>
<asp:Button ID="StepNextButton" runat="server" CommandName="MoveNext"
Text="Create User" ValidationGroup="CreateUserWizard1" />
</CustomNavigationTemplate>

is obsolete.

Is there something I can type that will programmatically achieve what this button performed?