An anniversary is not the same as a birthday!
An anniversary is the celebration of a special event on the date
it originally happened, for example a wedding anniversary.
A birthday is the celebration of the person who was born on that day. On this day you wish him or her a "Happy Birthday!".

To have - in literal sense: (hebben)
- I have (got) a car.                        
- I have (got) an idea.                    

To have - in fixed expressions:
- Let's have something to eat.       
- Have a seat. = Sit down.                           

- What can I do for you?               
- I was wondering if...                    
- What a coincidence!                    
- Yeah.                                          

(Ik heb een auto.)
(Ik heb een idee.)


(Laten we iets te eten nemen.)
(Zet u neer. / Gaat u zitten.)

(Wat kan ik voor jou doen?)
(Ik vroeg me af of... )
(Wat een toeval!)  
('Ja' tijdens gesprek tussen vrienden.)