I don't understand this with Scala hasmaps: How do I create a value or update one if it does not exist?

I am tryng to count the number of characters in a list of Strings.

I've tried this code but it doesn't work :

 def times(chars: List[Char]): List[(Char, Int)] = {
     val map = new HashMap[Char, Int]()
     chars.foreach(
        (c : Char) => {
           map.update(c, map.get(c) + 1)
        })
 } 

I understand the returning type isn't correct. But is my foreach loop wrong? Is there a prettier way to write it?