Question: The first button is

```
<button class="btn bid-hotel-btn" type="button" onclick="buyNow(0,false)">Beli Sekarang</button>

```

and the second button is

```
<button class="btn bid-hotel-btn" type="button" onclick="buyNow(1,false)">Beli Sekarang</button>

```

The difference is only the `onlick` event on `HTML` and I want to automatically click one button.

Answer: 
As was stated by MilanG, logo is rendered in your page template (default `page.tpl.php` or theme suggestion) using `$logo` variable. This variable is set in [`template_preprocess_page()`](https://api.drupal.org/api/drupal/includes%21theme.inc/function/template_preprocess_page/7.x), and the best way to change it is to use the same preprocess function in your theme:

```
function mytheme_preprocess_page(&$variables) {
  $logo_path = '/' . drupal_get_path('theme', 'mytheme') . '/logos/';
  // Alter logo under some conditions
  if ($first_condition) {
    $variables['logo'] = $logo_path . 'logo1.png';
  } elseif ($second_condition) {
    $variables['logo'] = $logo_path . 'logo2.png';
  } elseif ($third_condition) {
    // Hide logo. Your page.tpl.php must contain 
    // something like <?php if ($logo): ?>
    $variables['logo'] = null;
  }
  // etc.
}

```
The "standard" way for printing logo is printing `$logo` variable from `page.tpl.php` template. But you don't have to do it that way at all.

I.e. you can add your php code which will alter logo html code the way you like.

Or, you can place logo html inside static blocks and set for every block on what pages should it appear (in block settings). And of course create "logo" region for your theme.