www1.idc.ac.il/tecs is an old site. The current site is www.nand2tetris.org, as tungsten linked in her post.
The book chapters are not available online. If you want to do part II on your own, you can read the Powerpoint slides that are on the nand2tetris site, search this forum for answers and ask new questions.
Also, the Coursera course for part II is about to start. You should be able to sign up now and start previewing the videos.
https://www.coursera.org/learn/nand2tetris2--Mark