send email code not working

I have 2 text boxes where user enters email and text respectively and a button if u click should send the text to the email specified. here is the code i have tried but its not working. can someone tell me what iam missing. Please help.
Imports System.Net.Mail

Partial Class Default2
    Inherits System.Web.UI.Page

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim sb As New StringBuilder
        sb.Append("Email Address: ")
        sb.Append(TextBox1.Text)
        sb.AppendLine()
        sb.Append("Comment:")
        sb.Append(TextBox2.Text)

        ...