NEED HELP : DWI Language display in WP

Hi WP-Sifus,

Here’s the scenario :

Current Situation: Translation using Google

<a href="/en" /><img src="<?php bloginfo('template_directory'); ?>/images/btn_en.png" /><a href="http://translate.google.com/translate?sl=en&tl=ru&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=www.abc.com" /><img src="<?php bloginfo('template_directory'); ?>/images/btn_bm.png" />

(simple word : BLOG in english , and a button to translate to russian lang for example)

RESULT : EVERYTHING CHANGED TO RUSSIAN LANG.

NOW NEED HELP fROM WP-SIFUS :p

i’ve seen a theme support other language ( not .po or .mo but in .php )

example : language folder > spanish.php

in spanish.php :

<?php
DEFINE('HOME', 'Portada');
DEFINE('LATEST_STORIES', 'Actualidad');
DEFINE('SEE_MORE_NEWS', 'Ver más noticias');
DEFINE('LATEST_NEWS', '¡Lo Último');
DEFINE('SEARCH', 'Buscar');
DEFINE('RSS_FEED', 'Feed RSS');
DEFINE('FEED_NEWS', 'Feed de noticias');

?>

Back-end remains english.Front end need to support dwi language.

Only button, h2, and etc need to be changed. NOT THE POST.

QUESTION:
Do i need to translate the above way or there is another way to translate everything mentioned.

permalink remains. 1 blog , 2 language.

Kindly advise.