Theory:

Use of have/has in Affirmative/Positive sentences:
S + have/has + V3 + O  
 
S - subject: I, we, you, they, he, she, it, Mary, John …
V3 - the Past Participle of the verb (the verb in the third form): written, eaten, worked, …
O - object
 
S
have/has
V3
O
I
have
eaten
two apples
We
have
eaten
two apples
You
have
eaten
two apples
They
have
eaten
two apples
He
has
eaten
two apples
She
has
eaten
two apples
It
has
eaten
two apples
  
Important!
Short forms:
 
have = 've
I have eaten = I've eaten
 
has = 's
She has eaten = She's eaten