How to access child control existing inside control ?

Hi friends,
First of all, following is the code snippet for your reference:
<div class="signupcontainer">
    <asp:Panel ID="pnlSignUp" runat="server">
        <asp:CreateUserWizard ID="CreateUserWizard1" runat="server" ....>
            <WizardSteps>
                <asp:CreateUserWizardStep ID="CreateUserWizardStep1" runat="server">                   
                    <ContentTemplate>
               ...