The Stone Base project consists of a main source file that provides a framework. It may be compiled together with any number and combination of "sections" to create a game incorporating all those sections.
collab0_main.inf - The main source file. It should not have to be modified at all. This is the one you actually compile, and the compilation will automatically include all the sections specified in collab0_sections.inf.
collab0_sections.inf - This source file must be in the same directory as the main file in order to compile the game. The sections file must be edited to include the filenames of all the collaborative sections you wish to use. The example sections file includes the filenames of the two example sections given below. It also has directions for editing it to include different files.
collab0_jde0.inf - An example section, the "Rock Room". This is the smallest, most bare-bones section possible. The source also has comments detailing how to create a section that works with the framework.
collab0_jde1.inf - A second example section, the "Blue Testing Area", more elaborate than the Rock Room.
To create interactive fiction with Inform 6, first you need to create an Inform 6 source code file. These are text files (usually with a .inf extension), and they may be created and edited with any text editor. (Or you can see the top of this page for projects!)
Once you have an Inform 6 source code file, you need to compile it. To do this, you must download two things:
An Inform 6 compiler for your operating system
A set of Inform 6 library files (same for all operating systems)
As long as the compiler, library files and source code file(s) are all in the same directory, it should be a simple matter to run the compiler with the source code filename as an argument. (On Windows, it should be done from a Command Prompt.)
To learn about programming in Inform 6, see the Inform 6 manuals. If you have any experience programming (Inform 6 has a C-like syntax), you can jump right in with Chapter III, Section 7 of the Inform Designer's Manual. I've also heard good things about the Inform Beginner's Guide, though I haven't read it myself.
Compiling Inform 6 code creates Zcode files. To play them, you need a Zcode interpreter appropriate for your operating system. (Zcode is like Java or Flash in this respect.)
The Interactive Fiction Wiki: How can I download and play IF? I can't do any better than this page in summarizing interactive fiction interpreters.