Smalltalk is an object-oriented, dynamically typed, reflective programming language.

There are several Smalltalk implementations. Iliad is currently available for GNU Smalltalk, Squeak and Pharo.

Canol Gokel's book "Computer Programming using GNU Smalltalk" is available as a free e-book, or you can buy a printed version. The book is under a dual CC-BY-SA and GFDL license.

The GNU Smalltalk manual includes a tutorial. An online version is available.

There are many other free books about Smalltalk. They can be an extremely rich resource for anyone wishing to learn Smalltalk or even other dynamically typed, object-oriented programming languages.