There are no such things as "stupid" questions. However if you think your question is a bit stupid, then this is the right place for you to post it. Please stick to easy to-the-point questions that you feel people can answer fast. For long and complicated questions prefer the other forums within the support section. Before you post please read this
Can you see Korean characters in general? If yes you have to change the Character Encoding in Firefox Edit > Preferences > Contents tab > the Advaced tab under Fonts and select Korean in the drop down menu If not you also have to install scim I believe, but perhaps that's not needed for FF to work properly
Don't fix it if it ain't broken, don't break it if you can't fix it
Heh, I got it working now. I did a different thing, I went to Language Support in Administration and I selected some laguage like Korean/Japanese/Chinesse, then it downloaded some package and fonts :3, I can see it now. Thanks.