Adding to MAMP database in SQL/PHP

Question

I made a program that pulls questions from a database for people to answer.
When they answer correctly the next question button pops up.
It also needs to increase the score of that user by 1, how do I tell it to do that?

The database

if($answer === $dbanswer) {
        echo "correct! (creates button that goes to Next Question)

   //This is the part I want working.   

   UPDATE users   
   SET score = score + 1    
   WHERE id = this user's id

} else
   echo "incorrect, try again ";