I learn Smalltalk a few years ago to port a C++ interactive geometry software (http://drgeo.eu) to Squeak/Etoys then Pharo. I can testify documentation was never an issue, there are plenty of free books to learn from and a very helpful and talented community.

Smalltalk is still so revolutionary in its concepts, I am afraid you have to do your home work to get it and work on the text book.