In 20 seconds of this video,
How can I make the waves?

Or are there any tutorials I can refer to?
And Whitewater rendering.
Is it particle?
Is it volume?

There are multiple ocean tutorials online. Just make sure you choose one that is relevant to the Houdini version you are using, because the water tools have changed with major versions. Pluralsite has a good one called Intermediate Ocean FX you can check out.