There are many aspects to learning the creation of interactive fiction. Here we mostly undertake to explain approaches to using Inform, and leave the larger questions of craft and design for elsewhere.
Inform is fundamentally a system of rules, organised into rulebooks. As you learn the system, you gradually work with more and more of these.
There are two interlinked manuals built into every copy of the Inform application: if you've downloaded Inform, you already have them. But they are also available to read or download separately from this website.
Writing with Inform is an overview of the language, beginning with the simplest kinds of construction (such as building a map of rooms, objects, and doors) and working its way up to more advanced tasks.
The Recipe Book approaches the problem of authorship from a different perspective. Instead of trying to teach the language from start to finish, it is organized for the author who wants to accomplish something specific.
The manuals anticipate only two of the possible ways that someone might want to learn a language such as Inform; there are many others, and members of the interactive fiction community have been kind enough to fill some of the gaps by contributing their own tutorials and variations.
There are several tutorials written specifically for classroom use or for teaching young people to use Inform; these are listed with the teaching resources.
Inform 7 for Programmers by Ron Newcomb introduces many of Inform's concepts in programming terms for authors with a background in traditional programming languages.
The Inform 7 Handbook by Jim Aikin is written with young people's reading levels in mind, but may be a welcome step-by-step getting started guide for adults as well.
Neither Writing with Inform nor the Recipe Book is designed as a reference guide to the syntax of Inform. Instead, each project's Index pane provides a ready reference to many aspects of the system, and is updated with each compilation so that it also includes elements created by the author or added by one of the extensions being used.
The Syntax Crib (a plain text file) lists standard phrasings associated with various tasks.
The Chart of Rules (a PDF) is a visual guide to Inform's rules and rulebooks, showing which rules and activities are invoked under which circumstances.
Inform 7 Cheat Sheet by Mark-Oliver Reiser (a PDF) is a condensed overview of many of Inform's core concepts.