Drupal Form API .  

Step 1. Create search form using

Step 2. Register our theme in Drupal theme registry using hook_theme().

Step 3. Create search-form.tpl.phpfile to theme this search form. 

function search_form() {
    $form['str'] = array(
    '#type' => 'textfield',
    '#size' => '32',
    );
 
    $form['category'] = array(
    '#name' => t('category'),
    '#type' => 'select',
    '#options' => array('0' => t('All'), '1' => t('Bars'), '2' => t('Restaurants')),
    );
 
    $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Search'),
    );
 
    return $form;
}

function search_theme() {
  global $theme;
 
  return array(
    'search_form' => array(
      'arguments' => array('form' => NULL, 'theme' => $theme),
      'template' => 'search-form',
    ),
  );

<table cellspacing="0">
    <tr>
        <td class="container-inline"><strong>php print t('Search');?>strong> php print drupal_render($form['str']); ?>td>
        <td class="container-inline"><strong>php print t('Category');?>strong> php print drupal_render($form['category']); ?>td>
        <td>php print drupal_render($form['submit']); ?>td>
    tr>
table>
<?php
print drupal_render($form);
?>