I'm not exactly sure how the SUSE installer works, but if it's anything like the ones I've experienced, then it was probably just "secondary language support" that was enabled, and not a complete language environment. That makes sure that the OS and file system can handle the character sets and special features of the language, but it doesn't actually set up anything that uses it. So you still have to make sure that your desktop environment and all of your programs are installed with the proper i18n (internationalization) support (if any), and you'll need to install an input method editor that can handle the language if it's not based on a western alphabet (I like scim myself. It can handle lots of different languages and IME clients).
I believe SUSE uses KDE as its default desktop, so assuming you're using it, you can go into the KDE control center and change the language and keyboard settings to the one you want to use. There may also be some settings you can use in YAST or whatever they call their administrative tool. When installing a program, check to see if it also has an i18n package in the alternate language. And SUSE is probably already set up that way, but if not, it's best to use a UTF-8 encoding for your base system character support.
Other than that, I really can't give you any details. You can probably get the best help in a forum based in the target language.