Add a tutorial to the readme

README.md

@@ -4,10 +4,35 @@ Modding tools for Backyard Baseball 2001.
 
 If you don't want to download anything, you can always [browse the scripts online](https://github.com/whatisaphone/inside-baseball/tree/browse).
 
-## Getting Started
+## A Quick Tour
 
-- [Download the latest release](https://github.com/whatisaphone/inside-baseball/releases)
-- Run `inside-baseball --help`
+Let's extract the game scripts, modify one of them, and rebuild the game.
+
+Before you start of course, [download the latest release](https://github.com/whatisaphone/inside-baseball/releases). Open a terminal and run `inside-baseball --help` to make sure it works.
+
+1. Locate `baseball 2001.he0` from your copy of the game. Make sure the disk files (`baseball 2001.(a)`, etc) are in the same directory.
+
+   Extract the assets to a new project directory (this demo uses `~/Documents/bb2001`):
+
+   ```sh
+   inside-baseball project extract '/path/to/baseball 2001.he0' -o ~/Documents/bb2001
+   ```
+
+   This will write project.txt to the output directory, as well as one directory per room.
+
+2. Modify a script. The file `baseball/RMDA/LSC2/2060.bin` contains the hover text for the main lobby. Open it in a hex editor and change "Meet the players" to "Meet the Fockers".
+
+3. Rebuild the assets. This will **overwrite** `baseball 2001.he0` and other files in the same directory!
+
+   You need to pass `-d` with a disk number. Remember in the previous step, we modified the room "baseball". Open project.txt from step 1. Next to "baseball" you'll see `disk=2`, so the disk number is 2.
+
+   ```sh
+   inside-baseball project update ~/Documents/bb2001 -o '/path/to/baseball 2001.he0' -d 2
+   ```
+
+Now when you run the game, it will use your changed text!
+
+![Screenshot of game after rebuilding](docs/demo-finished.webp)
 
 ## Contributing