hook_form_alter is your friend here.
theme.php , ..
, .
function bhha_form_alter(&$form, &$form_state, $form_id) {
if ($form_id == 'user_login') {
$form['#prefix'] = '<div class="loginForm">';
$form['#suffix'] = '</div>';
$form['name']['#title'] = Null;
$form['name']['#description'] = Null;
$form['name']['#attributes'] = array('placeholder' => t('username'));
$form['name']['#size'] = '30';
$form['pass']['#title'] = Null;
$form['pass']['#description'] = Null;
$form['pass']['#attributes'] = array('placeholder' => t('password'));
$form['pass']['#size'] = '30';
$form['actions']['submit'] = array('#type' => 'image_button', '#src' => base_path() . path_to_theme() . '/images/Login.png');
$form['links']['#markup'] = '<a class="user-password" href="'.url('user/password').'">' . t('Forgot your password?') . '</a>';
$form['links']['#weight'] = 540;
}
}
, , . , , .
, , :
function THEME_NAME_form_alter(&$form, &$form_state, $form_id) {
if ($form_id == 'FORM_ID') {
$form['#prefix'] = '<div class="loginForm">';
$form['#suffix'] = '</div>';
$form['name']['#prefix'] = '<div class="formRow">';
$form['name']['#suffix'] = '</div>';
}
}