Add creates details and example usage

README.md

@@ -21,6 +21,29 @@ $ cargo build
 $ cargo test
 ```
 
+## Example Usage
+
+MagickWand has some global state that needs to be initialized prior to using the library, but fortunately Rust makes handling this pretty easy. In the example below, we read in an image from a file and resize it to fit a square of 240 by 240 pixels, then convert the image to JPEG.
+
+```
+use magick_rust::{MagickWand, magick_wand_genesis};
+use std::sync::{Once, ONCE_INIT};
+
+// Used to make sure MagickWand is initialized exactly once. Note that we
+// do not bother shutting down, we simply exit when we're done.
+static START: Once = ONCE_INIT;
+
+fn resize() -> Result<Vec<u8>, &'static str> {
+    START.call_once(|| {
+        magick_wand_genesis();
+    });
+    let wand = MagickWand::new();
+    try!(wand.read_image("kittens.jpg"));
+    wand.fit(240, 240);
+    wand.write_image_blob("jpeg")
+}
+```
+
 ## Generating Bindings
 
 To generate the ImageMagick bindings, we use [rust-bindgen](https://github.com/crabtw/rust-bindgen), which reads the C header files and produces a suitable wrapper in Rust.