Talking about the present
The page on time and tense  deals with all the basic features of "presente indicativo."
 deals with all the basic features of "presente indicativo."
The verb "stare" followed by a gerund is often used to describe actions in progress: "Piove" 
  "Sta piovendo" (
 "Sta piovendo" (  It's raining).
 It's raining).
The main difference is that there is free choice between the two options in It. while the "progressive form be + -ing is normally mandatory in Eng.
The It. tense that most closely corresponds to the Eng. present perfect tense is not a present at all but "passato prossimo" - see the page on past tenses 