how to create a custom form and embed it on a node Right now, I want to create a form which only have an email textfield and a submit button.

This is what I did in my "custom_request_price.module":

function custom_request_price_form(&amp;$form, $form_state) {

  $form['email'] = array(
    '#type' =&gt; 'textfield',
    '#size' =&gt; '20',
    '#maxlength' =&gt; '255',
    '#required' =&gt; TRUE,
  );
  $form['email']['#attributes']['placeholder'] = 'Email Address';

  $form['submit_button'] = array(
    '#type' =&gt; 'submit',
    '#value' =&gt; t('Send');
  );
}


However, I don't know how to embed it to my article. I don't want to add this into a menu or make this as a new page. What I want to do is: when I open my article page, it directly showed up and visitors can enter their email address and simply to click "send" button. 

My search:
For doing this, I thought I need to add "drupal_get_form()" in my node-article.tpl.php to show this form on my article page. I am totally new for doing this. I don't know how to add form-ID in my custom module. Also, I don't know whether this is the correct way to embed my form.
The way I would go about it is to create the form within a Drupal block. In this manner, you could configure when &amp; where the form could be placed on the page and with what types of content. You also wouldn't have to edit your theme if you'd ever wanted to add the form to another type of content.

Look at hook_block_info() &amp; hook_block_view(), and reference the user module's implementation (user_block_info() &amp; user_block_view()) for how it create its user login block.