Gallery2 joomla 1.0.15

I have gallery2 .Default is English and users can switch to Czech language if they like to or if they have it set up as default language or if browser language is detected.Is working when I direct access gallery2.

I installed joomla 1.0.15 and integrated this gallery in joomla.Is working in English only.
In Joomla i selected code/decode utf-8 in gallery2 bridge config.(hoping for this to show correctly other language characters)

What do I need to do for users to change language in joomla to Czech when they require it?
How do i make the integrated gallery to reflect this language change not only in joomla but also in gallery?

Bottom line how to make joomla/gallery2 conveniently 2 language capable?
Just talking about the static content for now,like buttons instructions registrations....

my own Linux server
ssh access....