It's easy! Although facebook failed at it! At one time, facebook tried to add this feature themselves - but never came up with the idea of recording it yourself. Hah!
So don't mess around with their various phonetic spellings. Use saymaname to record your name how YOU want to say it, then paste the link into your facebook profile as a 'website'.
In fct, register NOW! Don't waste time.
Here's a video showing you how to add the link to your profile.