The following websites offer tactical puzzles and/or the facilities to play chess on-line. Some features are accesssible free of charge.
Some of the following sites may be useful for learning to play chess. They are free at beginners levels.
(The Official Laws of Chess)
FIDE Laws with comments for Arbiters - CAA
FIDE Arbiters' Manual 2018
Here are some books worth considering. To buy them, please see the online shopping links on the Links page:
For learning opening strategy: