Config stringlist help

Hey guys, how can i add something to a string lost that is in the config, so like

Derp:
- Herp

Something like that

Ok, for example. I have a arraylist

PHP:

// Declare it.
List<String> test = new ArrayList();
// Add something to it.
test.add("derp");
// Set it to config
config.set("classes", test);
// Which then returns
classes: []

got it... i just failed...

TnT please close this (or SwearWord | md_5 | NuclearW )

EDIT by Moderator: merged posts, please use the edit button instead of double posting.