How to add text to the user registration form?
You can use hook_form_alter like this. 

  function MODULENAME_form_alter(&amp;$form, &amp;$form_state, $form_id){
    switch($form_id) {  
      case 'user_register_form': // the value we stole from the rendered form  
        $form['cutomtext'] = array(
        '#type' =&gt; 'item',
        '#markup' =&gt; '&lt;div &gt; Your text goes here... &lt;/div&gt;',
        '#weight' =&gt; 1, // Adjust so that you can place it whereever 
        );
        break;  
    }  
  }


Form API Reference

Also you could try hook_form_FORM_ID_alter

Usage :

function hook_form_FORM_ID_alter(&amp;$form, &amp;$form_state, $form_id) {
  // Modification for the form with the given form ID goes here. For example, if
  // FORM_ID is "user_register_form" this code would run only on the user
  // registration form.

  // Add a checkbox to registration form about agreeing to terms of use.
  $form['terms_of_use'] = array(
    '#type' =&gt; 'checkbox',
    '#title' =&gt; t("I agree with the website's terms and conditions."),
    '#required' =&gt; TRUE,
  );
}