This is a synchronic siteswap.
(Both hands throw at the same time.)
Start with 504.
Then change 5 to 6x and throw the same pattern but in synchronic version.
Then try (6,4x)(4x,2)(4,4)*
- this will teach You the heights of throws.
At last try (6x,4)*.

Mark * means to repeat on the other side .. so (6x,4)* means (6x,4)(4,6x).