You might want to use KLettres to help you learn a new language. By using , you will see a new dialog with the list of available languages (you need to be connected to the Internet to use that feature).
Click on the Install button on the right of the language you want to install. You'll see the progress bar indicating how the download is progressing. The next screenshot shows Danish being downloaded.
Please note that some files have several MB so it might be slow depending on your connection.
After the file is downloaded, it is automatically installed and when you close the Get Hot New Stuff dialog you'll see the new language in the menu and you can use it immediately.
When a language is downloaded, you then can see the Install button turning to Uninstall and a green tick appears next to the language name to tell you that this language is available in KLettres.
The next screenshot shows Danish installed.