There are several good Smalltalk dialects, such as Squeak, Pharo, and Dolphin Smalltalk (for Windows). I usually recommend Pharo because it’s the most actively developed language with the largest user community.
At the Pharo homepage, you can download the Pharo software for either Windows or macOS (I presume you’re not using Linux).
The best Pharo book for beginners is Pharo by Example 50. It is free to download. After you’ve installed Pharo, just dive into this book.
The Pharo MOOC is a series of videos (with English subtitles) and PDF files in both French and English. They contain step-by-step instructions for how to use Pharo to write a web application.
To get you warmed up for all this, try this gentle online Smalltalk tutorial.
If you like videos, there are some excellent ones from the late James Robertson, a famous Smalltalk evangelist.
There are two other free books that I like, although they’re not for Pharo. One is for Cincom Smalltalk; the other is for GNU Smalltalk. Although they’re not Pharo-specific, they may help you with Smalltalk programming concepts.