How to write page.tpl.php where the HTML files is more than one?
Actually you may have to create a page--front.tpl.php for index page of your website and a page.tpl.php to have all other pages.

you could also use theme debug mode too. it can be enabled by including the following in settings.php,

$conf['theme_debug'] = TRUE;

The ablove will include theme suggestions as html comments, that helps you theming your pages.