Take a look at this review of twelve tenses using example sentences. Getting the tenses write when you are speaking is going to make it a whole lot easier to make yourself understood.
"I play tennis."
"I played tennis."
The Present Perfect Continuous is used to talk about events which started in the past and may still be continuing now - this tense usually has a link to the present time.
subject + have / has + been + -ing verb
"He has been waiting for 20 minutes."
