Adding labels to dynamic map service layer

[RuchiraWelikala]

Hi,
As the title suggests, I'm trying to add labels to a dynamic map service layer.
I found something here: https://developers.arcgis.com/javascript/jsapi/labelclass.html

My DMSL has 5 layers in it so am I able to specify the layer that I want labelled?
I've been at it for a while and just not getting it.

Any help would be much appreciated!

Thanks,
Ruch