Where does one get basic notions of Buddhism when starting with Mahayana?

Maybe it's better to use an example. I believe one of the very first Mahayana sutras one is expected to learn is the Heart Sutra. But when you read it, you immediately see things like 'skandhas' and 'dharmas'. If you start with Pali Canon, you can basically find all about them in the Sutta Pitaka. But if you know nothing about Theravada, where in the Mahayana teachings do you find those basic notions? What will tell you about karma, dependent arising, dharmas, worlds structure and so on?