perfect continuous

I don't understand the difference between present perfect contunious tense and perfect tense.When do I use which tense ?

The perfect tense describes an action completed: "I have eaten". It uses the verb "have" (or had) and the past participle of the action verb ("eaten")

The past perfect continuous describes longer or continuing actions: "I have been eating". Use have (or had) again + been, then use the present participle of the action verb ("eating")

I hope I haven't confused you further :)