How do I should start to master the Portal Content Management in NWDI?

Hi there,

    I am new here, and I am developing sapui5 related application, and  it is NWDI based application, And along with the development, I gradually feel I need more understand about NWDI, especially Portal Content Management,  but there are many contents and I cannot get a clear understand throught reseaching them by myself, so I hope some experts can give me a definite guide or learning materials, thanks in advance.