the main thing here is Einstein's seminal paper on the photoelectric effect in 1905 that explained the phenomenon using Planck's earlier theory of quantised EMR energy. Einstein however, called the packets of energy "photons" and not just "quanta".
you just have to make sure you know how Einstein used this newly discovered Quantum theory of Planck's to explain the photoelectric effect, and also things like the work function, kinetic energy of the liberated electrons, etc...
his contribution to quantum theory is also that he agreed with Planck over the idea of quantised energy and helped establish Quantum Mechanics from there (although he did not like many implications of quantum mechanics at all).