This will be very short as I have picked this up, and I can’t guarantee that I am correct. But basically:
There is common law, as adopted from Britain, as with most countries that Britain colonised.
Then there is statutory law, legislation made by parliaments.
And in addition to the above, Muslims also come under Sharia law. At present, Sharia law is not applied to non-Muslims.
Malaysia has a constitution which you can find online in English. It is reasonably short and quite easy to read.