I'm translating "I remember how to do it." I thought it was "Mwen sonje kijan fe l" (I looked up "fe" and it is translated as "to do") but I'm told the better translation is "Mwen sonje kijan pou fe l." Why "pou"? Thank you Mandaly!

Mwen sonje kijan pou fè'l  is the correct translation.  "pou" is the preposition which translates the English "to" in this instance.  If you omit the "pou" in the Creole sentence, it would sound like "I remember how do it".  Something will be missing.
Haitian Creole ↔ English Reference (a work in progress at this time)