Can you explain what FCE means? Generally, whether you can teach a language depends on:
* the nature of the qualification you have
* your experience in the language
* the particular qualifications your employer requires
* any rules of laws about the qualifications required to teach primary, secondary school students in your country's education system
Of course, there is nothing to stop you giving private lessons to anyone who is willing to pay you but I assume you are asking because you want paid employment as a teacher.