Hi fkz2899,

Instead of using txtarea use asp TextBox and set the TextMod to MultiLine.

So that you can access the value in code behind.

Then you can insert the value in database.

Check this example. Now please take its reference and correct your code.

SQL

CREATE TABLE CKEditor
(
    Description NVARCHAR(MAX)
)

HTML

<script type="text/javascript" src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<script type="text/javascript" src="https://cdn.ckeditor.com/4.9.2/standard/ckeditor.js"></script>
<script type="text/javascript">
    $(function () {
        CKEDITOR.replace('editor');
    });
</script>
<table>
    <tr>
        <td>
            <%--<txtarea id="editor" name="editor1" runat="server">
            </txtarea>--%>
            <asp:TextBox runat="server" ID="editor" TextMode="MultiLine" />
        </td>
    </tr>
    <tr>
        <td>
            <asp:Button ID="save" runat="server" OnClick="save_Click" Text="Save" />
        </td>
    </tr>
</table>

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient

Code

C#

protected void save_Click(object sender, EventArgs e)
{
    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand("INSERT INTO CKEditor (Description) VALUES(@Content)"))
        {
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@Content", HttpUtility.HtmlEncode(editor.Text));
            cmd.Connection = con;
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
}

VB.Net

Protected Sub save_Click(ByVal sender As Object, ByVal e As EventArgs)
    Using con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
        Using cmd As SqlCommand = New SqlCommand("INSERT INTO CKEditor (Description) VALUES(@Content)")
            cmd.CommandType = CommandType.Text
            cmd.Parameters.AddWithValue("@Content", HttpUtility.HtmlEncode(editor.Text))
            cmd.Connection = con
            con.Open()
            cmd.ExecuteNonQuery()
            con.Close()
        End Using
    End Using
End Sub

Screenshot

Form

Database record after inserted with HtmlEncode and without HtmlEncode

Note: Refer the below article to avoid the error.

A potentially dangerous Request.Form value was detected from the client 

ASP.Net Error: A potentially dangerous Request.Form value was detected from the client