trying to use asp.net button to send a html form

my problem is i need to have a check out button either asp:button or the form submit that will run c# code and then submit the form.

1. user press button
2. c# code will create order
3. c# code will run code for shipping detail (buy shipping)
4. C# code will run code for accounting
5. submit form that will display an iframe

Code for form


<div id="myForm" style='display:none'>
  <div id='inline_content'>

       <script>
        $(".inline").colorbox({
            inline: true,
            opacity: 0.5, // overlay a bit less dark
            innerWidth: 640,
            innerHeight: 390,
            onComplete: function () { document.OutputForm.submit() }
        });

       
    </script>
    <form name="OutputForm" method="post" action="https://test.authorize.net/payment/payment" target="payframe" id="LinkTo" class="ShowForm">
      <input type="hidden" name="Token" value="<%=token%>" />
       </form>

        <iframe id="payframe" name="payframe"></iframe>
</div>