Present perfect

Aquí explican muy bien el uso del present perfect:
http://www.langust.ru/unit_el/unit_017.shtml
Y aquí para ver el uso de FOR / SINCE:
http://www.langust.ru/unit_el/unit_018.shtml

Se suele usar con los adverbios already, just, still, yet. Para repasar su uso:
http://www.curso-ingles.com/aprender/cursos/nivel-avanzado/verb-tenses-present-perfect/already-just-still-yet

How long...? Cuestiones habituales con la construcción How long + Present perfect:

 How long have you lived in this country/city/town?
 How long have you lived in your apartment/house? 
 How long have you been married?
 How long have you known your best friend? 
 How long have you studied English? 
 How long have you gone to this school?
 How long have you had your car/Cat/Dog/ Business/ House?
 How long have you been awake?
 How long have you smoked/ Dated/ Studied/ Traveled? 
 How long have you worked at your job?