After you've got a grasp of what these things are doing then you can move into the how. For that you will need some math background, with emphasis in calculus and probability.
After that, you can take a look at PRML. https://www.amazon.com/Pattern-Recognition-Learning-Informat...
Some people might prefer seeing things from another approach. http://pgm.stanford.edu/
Good luck.
After you've got a grasp of what these things are doing then you can move into the how. For that you will need some math background, with emphasis in calculus and probability.
After that, you can take a look at PRML. https://www.amazon.com/Pattern-Recognition-Learning-Informat...
Some people might prefer seeing things from another approach. http://pgm.stanford.edu/
Good luck.