These are some of my favourite prolog resources, not an exhaustive list by any means but in my opinion the best of the best. If you want a more exhaustive list then I suggest you look here
Swish is a great online tool to find some examples or prolog code and try them out in real time. You can also share your own efforts with others!
Markus Triska is an amazing resource for Prolog and touches on the basic to advanced.
Prolog Learning Materials
Everyone recommends these books, I have read 'The Art of Prolog' and it is very detailed.
Programming in Prolog (W.F. Clocksin and C.S. Mellish), Springer-Verlag, New York, 1981. (4th ed. 1994)