The present perfect simple expresses an action that is still going on or that stopped recently, but has an influence on the present. It puts emphasis on the result.
Form of Present Perfect

Positive Negative Question
I / you / we / they I have spoken. I have not spoken. Have I spoken?
he / she / it He has spoken. He has not spoken. Has he spoken?

For irregular verbs, use the participle form (see list of irregular verbs, 3rd column). For regular verbs, just add “ed”.
Exceptions in Spelling when Adding ‘ed’

Exceptions in spelling when adding ed Example
after a final e only add d love – loved
final consonant after a short, stressed vowel
or l as final consonant after a vowel is doubled admit – admitted
travel – travelled
final y after a consonant becomes i hurry – hurried

Use of Present Perfect

puts emphasis on the result
Example: She has written five letters.
action that is still going on
Example: School has not started yet.
action that stopped recently
Example: She has cooked dinner.
finished action that has an influence on the present
Example: I have lost my key.
action that has taken place once, never or several times before the moment of speaking
Example: I have never been to Australia.
Signal Words of Present Perfect

already, ever, just, never, not yet, so far, till now, up to now