This is a general response for those who don't understand that dictating in a foreign language actually has to do with your "keyboard" setting:
By default in the U.S., your iPhone comes with an English keyboard and you can thus do dictation in English for email, text messages and calendar/reminders/notes if you use those latter 3. To accomplish this, just touch the microphone that's just to the left of your space bar on the keyboard, speak, and click "Done" when finished. It will recognize works like comma, period, question mark, exclamation point, etc. as punctuation marks. If you try to speak French, it won't recognize what you're saying.
To add the French SPEAKING option, hit "settings", "general", "keyboard", "Keyboards", "Add New Keyboard...". Choose "French" and then specify that you want the "QWERTY" option so that it's the keyboard that we as Americans are accustomed to using as opposed to the true French keyboard. I capitalized SPEAKING just above because when one adds a keyboard one thinks of typing characters rather than speaking. But it's this "keyboard" addition which actually allows you to use another language in dictation. That's because, when your French keyboard, for example, is in use, the microphone next to the space bar will be ready for you to speak French instead of English.
To switch between languages, hit the "globe" icon to the left of the "microphone" icon. You will notice that when you're in French mode, the space bar will say "espace" instead of "space". Be ready to use French punctuation with words like "virgule", "point", "point d'interrogation", etc.
