How to submit Javascript/jquery form values from code behind vb.net?

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VB

ASP.NET

Javascript

jQuery

I have a javascript function that opens a popup form on button click. I need help with when user clicks "submit" it needs to fire my vb code behind to insert the data into my database.
I also need help with the submit button to fire the event. Do I do this in the javascript? or on the form in my table?
I haven't used popups much with jquery, so any help would be appreciated, or a different way to accomplish this.
Code Below:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.9/jquery-ui.js" type="text/javascript"></script>
<link href="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.9/themes/start/jquery-ui.css"
    rel="stylesheet" type="text/css" />

<script type="text/javascript">
    $("[id*=RegisterButton1]").live("click", function () {
        $("#modal_signup1").dialog({
            width: '325',
            height: '500',
            title: "Start Your 30 Day Trial Here",
            buttons: {
                Close: function () {
                    $(this).dialog('close');
                                },
                                Submit: function () {
                                    $(this).dialog('submit');
                                }
            },
            modal: true
        });
        return false;
    });
</script>

<asp:Button ID="RegisterButton1" runat="server" Text="Register Now!" />

<div id="modal_signup1" style="display: none; font-family: calibri;">
<table style="font-family: calibri; font-size: small; font-weight: bold" 
        align="center">
<tr>
<td>
NPN Number:
</td>
<td>
    <asp:TextBox ID="TextBox1" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your NPN Number (You Will Use This To Login)"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Password:
</td>
<td>
    <asp:TextBox ID="TextBox2" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter a Password (You Will Use This To Login)"></asp:TextBox>
</td>
</tr>
<tr>
<td>
First Name:
</td>
<td>
    <asp:TextBox ID="TextBox3" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your First Name"></asp:TextBox>
</td>
</tr>
<tr>
<td>
MI:
</td>
<td>
    <asp:TextBox ID="TextBox4" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Middle Initial"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Last Name:
</td>
<td>
    <asp:TextBox ID="TextBox5" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Last Name"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Address:
</td>
<td>
    <asp:TextBox ID="TextBox6" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Address"></asp:TextBox>
</td>
</tr>
<tr>
<td>
City:
</td>
<td>
    <asp:TextBox ID="TextBox7" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your City"></asp:TextBox>
</td>
</tr>
<tr>
<td>
State:
</td>
<td>
    <asp:DropDownList ID="DropDownList1" runat="server">
    <asp:ListItem Value="NC" Selected="True">North Carolina</asp:ListItem>
    </asp:DropDownList>
</td>
</tr>
<tr>
<td>
Zip:
</td>
<td>
    <asp:TextBox ID="TextBox8" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Zip Code"></asp:TextBox>
</td>
</tr>
<tr>
<td>
County:
</td>
<td>
    <asp:DropDownList ID="countylist" runat="server" DataSourceID="SqlDataSource2" 
        DataTextField="county" DataValueField="county">
    </asp:DropDownList>
</td>
</tr>
<tr>
<td>
Phone:
</td>
<td>
    <asp:TextBox ID="TextBox9" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Phone Number"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Fax:
</td>
<td>
    <asp:TextBox ID="TextBox10" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Fax Number"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Email:
</td>
<td>
    <asp:TextBox ID="TextBox11" runat="server" rel="ToolTip" data-placement="bottom" ToolTip="Enter Your Email"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2">
Security Question:<br />
What is 2+3? <asp:TextBox ID="TextBox12" runat="server" Width="50"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2">
    <asp:Button ID="SubmitButton" runat="server" Text="Start My Trial Now!"  
        onclientclick="return confirm('Register Now?')" OnClick="SubmitButton_Click" />
</td>
</tr>
<tr>
<td>

</td>
<td>

</td>
</tr>
</table>
</div>