I have read most topics considering language files, but I didn't find answer for this. Maybe I'm just stupid.
I started to translate Coppermine to finnish. Can I test it somehow? Can't choose finnish language from the dropdown menu in config file. I also tried to name my finnish.php to swedish.php, but it seems to not work like that. :D
In the following files:
include/functions.inc.php
include/select_lang.inc.php
search for swedish and copy the lines to make finnish versions of them.
force the use of a certain language by adding lang=yourlanguage to the url in the address bar, i.e. http://yoursite.tld/your_coppermine_folder/index.php?lang=finnish
Make sure that your language file name actually corresponds to this - for above example, your language file needs to be named "finnish.php" and reside inside the lang folder.
Please review the http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#translating section and the subsequent page http://coppermine-gallery.net/demo/cpg14x/docs/translation.htm