After installing LibreOffice 3.4.3, I gave a test run and scribbled something on the word processor. Immediately I noticed that the spellcheck was not working. My native language is not English, so I checked to see if the Language settings were correct. Open the “Options” window from the “Tools” menu. Selected “Language Settings > Languages”. Everything was correct:
I couldn’t find anything on the options manager that put spellcheck to work. Finally, inside the word processor, I selected “Tools > Languages > More Dictionaries Online”:
It opened a browser window on a OpenOffice Wiki page. After searching a while, I landed on the following URL: http://extensions.services.openoffice.org/en/dictionaries
I downloaded the extension corresponding to my desired language, a .OXT file, opened with the LibreOffice extension manager and installed it.
I restarted the Word processor and it just worked. HTH!