How can I get header part from my drupal 7 site?
Usually header part is included in drupal in page.tpl.php. 

Still you can do it by creating a function in your template.php

e.g. myheader() and calling it in page.tpl.php.

function myheader(){
$html = "&lt;div class='header'&gt;
 Insert header html
&lt;/div&gt;";
return $html;

}  


Other way you create a template using hook_theme in your custom module and call it in page.tpl.php.

e.g. it will be called in page.tpl.php by below code 

print theme('myheader'); 

//It will defined in custom module 


function mymodule_theme($existing, $type, $theme, $path)
{
  if($type == 'module')
  {
    return array(
      'myheader' =&gt; array(
        'variables' =&gt; array('var_name'=&gt;NULL),
        'template' =&gt; 'myheader'
      ),
    );
  }
  return array(); //will raise fatal error if void
}


and put a template in theme directory with name myheader.tpl.php

Hope it will help!