Template php

Hi, i’m building my site in english and spanish. I need to do some php so that when the site is viewed in english it calls the “single” catablog template and when it’s in spanish it calls the “single-spanish” catablog template i have created in order to show different tokens.

This templates don’t let me add php code so i’m wondering which file in the Ftp do i need to change in order to add these php lines for it to work the way i want it?

Please guys help me out, i have been days on this and if i don’t find a solution today i’ll have to try something else because my boss is putting pressure on me.

Thanks in advance. Im using qTranslate to translate the site by the way.

http://ww.wp.xz.cn/extend/plugins/catablog/