There are many ways for secure coding. I didnt get you what do you mean by secure HTML coding. (Actually there are many way to secure your programing coding like php or asp but not html.) In HTML, you just need to make captch and use post method for submitting form, thats all.
There is no secure HTML coding. HTML is static. Security is needed only for dynamic applications/behaviors. If you use JavaScript to accept/process user inputs, you have to escape it.