How to dynamically update web config file in asp.net using c#?

I want to configure my web config connection string in my aspx page. That mean I want to change my web.config file dynamically. User can change the connection string any time without touching the server. For that the below asp.net c# code will help you to change connection string , appsetting information and ect..  in dynamically.

private void SetConfigSettings()

        {

            try

            {

                // App setting settings

                System.Configuration.Configuration config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");

                //APPsetting value change

                System.Configuration.KeyValueConfigurationElement setting = config.AppSettings.Settings["SupportFormat"];

                if (null != setting)

                    config.AppSettings.Settings["SupportFormat"].Value = txtFormat.Text.Trim();

                //APPsetting value change

                System.Configuration.KeyValueConfigurationElement Pathsetting = config.AppSettings.Settings["Path"];

                if (null != Pathsetting)

                    config.AppSettings.Settings["Path"].Value = txtPath.Text.Trim();

                //Connection string changes

                string newConnectionString = "Data Source=" + txtServer.Text + ";Initial Catalog='" + txtDatabaseName.Text.Replace("'", "") + "';User ID=" + txtUserName.Text + ";Password=" + txtPassword.Text + ";Persist Security Info=True;";

                //Configuration openWebConfiguration = WebConfigurationManager.OpenWebConfiguration("~");

                ConnectionStringsSection sections = config.GetSection("connectionStrings") as ConnectionStringsSection;

                if (sections != null)

                {

                    sections.ConnectionStrings["ConString"].ConnectionString = newConnectionString;

                    ConfigurationManager.RefreshSection("ConString");

                }

                config.Save();

                lblMSG.Text = "Updated successfully!!!";

                lblMSG.ForeColor = Color.Green;

            }

            catch (System.Exception exc)

            {

                lblMSG.Text = exc.Message;

                lblMSG.ForeColor = Color.Red;

            }

        }