How To Wrap Drupal Form API in html div structure [in my Drupal theme files (.tpl file)]
It will be hard to implement this html as it is. You have to create a custom form using form api of drupal and use its arguments to make the html nearly same like your design. But still there will be css changes respectively. Let me edit Email field for you

    function mycustomform($form, &amp;$form_state){
    $form['email'] = array(
      '#type' =&gt; 'textfield',
      '#title' =&gt; t('Email address'),
      '#size' =&gt; 60,
      '#maxlength' =&gt; 128,
      '#required' =&gt; TRUE,
      '#prefix'=&gt;'&lt;div class="inputHolder"&gt;&lt;p class="sub-title-1"&gt;',
      '#suffix'=&gt;'&lt;/p&gt;&lt;/div&gt;',
      '#attributes'=&gt;array('placeholder'=&gt;'Enter your email address')
    );

    $form['password'] = array(
      '#type' =&gt; 'password',
      '#title' =&gt; t('Password'),
      '#size' =&gt; 60,
      '#maxlength' =&gt; 128,
      '#required' =&gt; TRUE,
      '#prefix'=&gt;'&lt;div class="inputHolder"&gt;&lt;p class="sub-title-1"&gt;',
      '#suffix'=&gt;'&lt;/p&gt;&lt;/div&gt;',
      '#attributes'=&gt;array('placeholder'=&gt;'Enter your password') // No use because it will show dots or *
    );
    $form['login'] = array(
      '#type' =&gt; 'submit',
      '#value' =&gt; t('Login'),

      '#prefix'=&gt;'&lt;div class="buttonHolder"&gt;',
      '#suffix'=&gt;'',
      '#submit'=&gt;'custom_user_login',  
      '#attributes'=&gt;array('class'=&gt;array('primary_btn')) // No use because it will show dots or *
    );
    $form['register'] = array(
      '#type' =&gt; 'submit',
      '#value' =&gt; t('Register'),
      '#submit'=&gt;'custom_user_register',
      '#prefix'=&gt;'',
      '#suffix'=&gt;'&lt;/div&gt;',
      '#attributes'=&gt;array('class'=&gt;array('primary_btn')) // No use because it will show dots or *
    );
return $form;
}

function mycustomform_validate($form, &amp;$form_state){
    //Add checks for already registered user
}

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

      if($uid = user_authenticate($username=$form_state['values']['email'], $password=$form_state['values']['password']))
    {
      user_login_submit(array(), array('uid' =&gt; $uid));
      return true;
    }
    else
    {
        return false;
    }
}

function custom_user_register($form, &amp;$form_state){
    $new_user = array(
  'name' =&gt; $form_state['values']['email'],
  'pass' =&gt; $form_state['values']['password'], // note: do not md5 the password
  'mail' =&gt; $form_state['values']['email'],
  'status' =&gt; 1,
  'init' =&gt; $form_state['values']['email'],

);

// The first parameter is sent blank so a new user is created.
$user = user_save('', $new_user);
if($user-&gt;uid){
drupal_set_message('User saved successfully');
}else{
    drupal_set_message('Error in saving user','error');
}
}


Hope it will help you.