Please explain the consequences of Planck's quantum theory

I don’t understand how did Planck solve the black body problem by the quantization of energy. My questions

1. What will the oscillators/atoms do with the energy that is not an integral multiple of hv. Suppose I give an energy of 1.5 hv. Will the body absorb 1hv and leave the rest?
2. Can anyone explain the correct graph of black body radiation using plancks quantization. I want to know why the intensity at certain wavelength was max. Why the intensity (as a function of wavelengths ) was increasing before that and why it decreased after that.

My background:- I am a high school student. My textbook just explained what black bodies are, showed the graphs, and said it could not be explained by classic laws but Planck explained it by introducing quantization. I want to know how exactly the equation nhv= E helped him to plot the correct graph.