CKEditor

    <script type="text/javascript" src="../ckeditor/ckeditor.js"></script>

         <div>
            <textarea id="editor1" name="editor1">
               <%= WriteEditor() %>
            </textarea>
         </div>
         <script type="text/javascript">
            var editor = CKEDITOR.replace( 'editor1' );
         </script>

         string ckInput = Request.Form["editor1"]; // save this to the db

      protected string WriteEditor() {
         return htmlContent; // the html saved previously or blank if new
      }

You can convert html control to server control by adding runat="server" in html side ,

such as

<textarea  rows="5" cols="5" id="editor1"  runat="server"></textarea>

then in the code behind  you can get or set the value using  editor1.Value

such as

Label1.Text = editor1.Value.ToString();     // to get the value of the editor

editor1.Value = "Hello CkEditor!";     // to set the value of the editor