When you're working on a project, it's probably best to make sure all the parts function individually, and then as a system, BEFORE you sew them into garments.
There's nothing you need to put in the code/sketch that says "hey, this is an Arduino!" or "hey, this is a Lilypad!"
The code has to compile and be uploaded to the processor, and to do that, you have to select the proper type of hardware from the Board menu. It may not mention "Lilypad" explicitly, I think they are functionally identical to the "Diecimilia" board type.