What's blorb?

It's the official resource format for Glk.

How do I make one?

There's a couple of programs out there, though they tend to be a little tricky to use or to adapt to a particular platform. Fortunately, I've also come up with some blorb utilities for DOS that should be reasonably portable

iblorb: the blorb-inform program suite:

Download iblorb as either source, MS-DOS binaries or (untested) Linux i386 libc6 ELF executables.