Here is the syntax, along with some other methods you might find useful:
//add to the end of the list
stringList.add(random);
//add to the beginning of the list
stringList.add(0, random);
//replace the element at index 4 with random
stringList.set(4, random);
//remove the element at index 5
stringList.remove(5);
//remove all elements from the list
stringList.clear();