s "chagren" ever used as a verb when I want to say "I miss you"? Eg.: Mwen chagren w I also know I can say: Ou manke m, Mwen sonje w.

Hi,
It is best to use chagren as an intransitive verb if using it as a verb.
Kè m chagren.
Mwen chagren.
Maybe you could say ou ban m chagren lè w pa la or kè m chagren lè w pa la.

Chagren n. - anguish, sorrow, grief, heartache, regret....
Chagren v. - to be filled with grief


Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Pitit fi mwen, se pou w aprann tande lè yo pale ou.

Thank you Willeen for sending in this beautiful poem:

Pitit fi mwen, se pou w aprann tande lè yo pale ou. 

Avanse pi pre, pou m bay de twa ti koze 
  
Met zorèy ou byen fen pou w tande lè yo pale ou.  
                  
Depi m te tou piti maman m te pase m mesaj sa a tou.      
   
Pawòl sa yo te toujou nan tèt mwen, yo te ede m pase tout gè katòz
                                     
Y ava itil ou pou w pase nan pikan, pou w manje tout kalite zèb...   

E lè w di vwazinaj yo lonè, y ava toujou reponn repè pou ou. 

Pitit fi mwen, se pou w aprann tande lè yo pale ou. 
    
      
Ou gen yon trezò nan men w pitit mwen, w ale lekòl toulejou. 

Se vre chimen an pa fasil e li chaje gèp panèl. 

Men fò w ou toujou sonje... 

Apre bondye, se li k manman w, se li k zanmi w, se li k manje w,  e se li k tout ou. 

Se pou w renmen li, anbrase li, ancheri li, ba li tout nanm ou. 

Paske tout kote w ap pase, se li k ap akonpaye w. 

Angle, franse, panyòl, doktè, agronòm, pwofesè ,..

Yo tout se li. Pitit fi mwen toujou koute lè yo pale ou.   

                       
Jodia dan pouri gen fòs sou bannann mi, 

Pa solèy leve sou ou pitit di m, lanati va ban m rezon sou ou . 

W ava bezwen pran yon tèt zegui nan on chan mayi. ou p ap trouve li.    

Lamizè gen gou anmè, soufrans san konfyans se kraze nana. 

Men paske ou te tande m, lanati va louvri bra l pou ou, 

Zetwal va bat bravo pou ou, 

Linivè va kontan paske ou te ede l. 

Pitit fi mwen...lavi mwen...koute lè yo pale ou.

By Willeen (2016)

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words

Mandaly, could you explain the rule, when to pronounce a hard "nn" as opposed to a nasal "en", such as in jén?

Sure.
If there is a double n or an accented letter before the n, then you will the "nn" prononciation, as in
kabann
lamàn
ijyèn
lapenn
reponn
sann
bann
pann
pàn
Otherwise it should bea nasal (non-resonating sound).
manman
tonton
lapen
san
ban
pan

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words