This is a practical oversimplification which will be right most of the time. For more detailed information see Mastery of the Tenses!
"have done" / "has done"
For general experiences without reference to when
- Have you seen this film?
- I have been to Russia.
- They have never been in a plane before.
For recent past events with an effect in the present.
- I have missed my bus, I am going to be late, sorry!
- She has prepared for today's exam well.
We often use just, already and yet here.
- I have just eaten!
- Haven't you finished that homework yet?
- She has already told you what she thinks!
For uncompleted actions.
- I have lived here for 20 years.
- He has worked there all this week so far.
- They have watched half the film so far.
For when the result of an action is important.
- I have run a marathon and I am very proud of it!
- She has fixed the car and it works great!
With AFTER to talk about the future, Present Simple also possible.
- I'll call her after I have spoken to him.
- I'll call her after I speak to him.
Attention: "I have been" and "I have gone" are different in meaning.
- I have been to the shops, and now I am at home.
- They have gone to the shops and they are still there.
Use the Present Perfect Simple , not Continuous, with state verbs usually.
- I have always loved you.
- She has known me all her life.
Use of just, already and yet is also possible with Past Simple in American English.
- I have just eaten.
- I just ate.