Once you've installed Spirit on your computer, the first thing to do is check that it's working. Start up Half-Life, and activate Spirit of Half-Life from the Custom Game menu. (If it's not in the list, or if the menu graphics don't change, something's gone wrong.)

After that, why not have a look in the maps directory; Spirit includes a fairly large number of demo levels for you to play with.

When you're bored of that, it's time to set up Worldcraft to make your own Spirit maps. If you're not sure how to do that, follow the instructions here.
(There are no instructions available for Quark, since I don't use or understand it. Sorry about that.)

Other information:

• Spirit FAQ
  Frequently asked questions about Spirit.
• Features
  A fairly readable summary that explains what you can do with Spirit.
• Spirit Entity Guide
  A reference, detailing every property of every entity in Spirit.

Credits:

The SpiritDemo level is by MR, somewhat modified by me. All other levels by me.

The spirit.ico icon was generated by MR, based on a graphic by me.

The menu background is by MR, somewhat modified by me. Menu titles and text are by me.

Thanks go to:
Autolycus at valve-erc.com, for his boundless support, and for hosting the Spirit website. Also for helping out at the Mod Expo.

Peter Coffey for being a generally good bloke.

Whoever came up with that lovely method for making rain.

Thanks, also, to the many many people (far too many to list here - you know who you are) who've sent me ideas, comments and bug reports.
Spirit wouldn't be the same without the sense of community.

Oh, and thanks to Valve, for obvious reasons.