System Preferences-%26gt;International
Then you can choose your IMEs. The language menu appears in the upper right hand corner of the screen. For Korean, there aren't that many different IMEs. For Spanish, however, there are keyboards for more or less every Spanish-speaking country in the world, so you'll have to choose the one you prefer.
You can also set a hotkey to switch IMEs so you don't have to click on the language menu every time you want to do so. If you're used to Windows, you may want to set it to left ALT + SHIFT since that's probably what you're used to.
