They don't teach you how to use one - to me, it's always been the same thing as using a ball pen, except you trade the convenience (you have to change the ink cartridge) for practicality (you can erase the ink with special eraser) while keeping some style (it's still ink, not pencil, kept for drawing).
Getting a new pen felt weird at first, but just like a new pair of shoes, you end up accustomed to it.
So it's interesting to read about fountain pens in America, where people talk about having to "learn" how to write with a fountain pain. It's seen as such a special, luxury or just nerd thing, while in France, it's just something common nobody really pay attention to.