how to populate textbox with new Row ID in windows form

I'm creating a windows form and currently in the process of creating the "create member" form.

Now i wish to show to the user inputting data what the new members ID will be. So i thought of trying to show the new row ID within a text box.

I've tried to attempt it below but having difficulty getting the result from the sqlCommand. Or maybe im going the wrong way around doing it ha

Can anyone see how i can apply the id upon load?

    private void frmAddMember_Load(object sender, EventArgs e)
    {
        using (var connection = new SqlConnection(Properties.Settings.Default.BioEngineeringDB))
        {
            connection.Open();
            using (var cmd = new SqlCommand("SELECT * FROM Users WHERE UserID=(SELECT MAX(UserID) FROM Users", connection))
            {
                //cmd.Parameters.Add("@MYVALUE", SqlDbType.VarChar).Value = comboBox1.Text;
                SqlDataReader re = cmd.ExecuteReader();

                if (re.Read())
                {
                    txtMemberId.Text = // result from the SQLCommand but i dont know how to get it