Unfortunately I personally don't have much experience with GLScene so I can't help you directly.

But after searching the web a little I found this: http://glscene.pbworks.com/w/page/6437712/TGLWaterplane
This should be a component for GLScene which adds water scene with optional waves so I'm guessing this is what you are essentially looking for. It comes with full source code so I'm guessing it should be enough for you to get started.