What is Maxwell Distribution, Thermal Equilibrium, Fluctuation and Wein's law?

[SMarioKingdom]

I was reading a book, 'Introducing Quantum Theory' by J.P.McEvoy, and I find it difficult to understand in details of Maxwell Distribution, Thermal Equilibrium, Fluctuation, Wein's law and Planck's quantum theory, so I am finding it difficult to follow Einstein's explanation of photoelectric effect. Can someone explain the following things I listed above, from scratch to top, including the explanation of graphs?

 

[Vanadium 50]

Have you seen this? https://www.physicsforums.com/blog.php?b=3588

 

[SMarioKingdom]

OK My question was too vague. I will ask much more specific question.