IMO the best intro book is Sutton's [1], it's extremely accessible (little math background needed) and covers all basic concepts. Work through David Silver's course (search youtube, it overlaps heavily with the book above) and then you are ready for something more advanced like [2] and you can start reading and implementing research papers.

[1] http://incompleteideas.net/book/the-book.html

[2] http://rail.eecs.berkeley.edu/deeprlcourse/