Input Box in asp.net with C#

protected void Page_Load(object sender, EventArgs e)
       {

           Button1.Attributes.Add("onclick","javascript:prompt('Enter Checkbox name.')");
       }

       protected void Button1_Click(object sender, EventArgs e)
       {
           String s="Viv";
           Response.Write(s);
           s ="<script language="'javascript'">return prompt('Enter Checkbox name.','name') </script>";
           Response.Write(s);

       }