Write a bunch of docs.

doc/site/classes.markdown

@@ -3,6 +3,8 @@
 Every value in Wren is an object, and every object is an instance of a class.
 Even `true` and `false` are full-featured objects, instances of the `Bool` class.
 
+Classes contain both *behavior* and *state*. Behavior is defined in *methods* which are stored in the class. State is defined in *fields*, whose values are stored in each instance.
+
 ## Defining a class
 
 Classes are created using the `class` keyword, unsurprisingly:
@@ -12,7 +14,57 @@ Classes are created using the `class` keyword, unsurprisingly:
 
 This creates a class named `Unicorn` with no methods or fields.
 
-**TODO: methods**
+## Defining methods
+
+To make our unicorn do stuff, we need to give it methods.
+
+    :::wren
+    class Unicorn {
+      prance {
+        IO.write("The unicorn prances in a fancy manner!")
+      }
+    }
+
+This defines a `prance` method that takes no arguments. To support parameters, add a parenthesized parameter list after the method's name:
+
+    :::wren
+    // Inside class...
+    prance(where, when) {
+      IO.write("The unicorn prances in " + where + " at " + when)
+    }
+
+Unlike most other dynamically-typed languages, in Wren you can have multiple methods in a class with the same name, as long as they take a different number of parameters. In other words, you can overload by arity. So this class is fine:
+
+    :::wren
+    class Unicorn {
+      prance {
+        IO.write("The unicorn prances in a fancy manner!")
+      }
+
+      prance(where) {
+        IO.write("The unicorn prances in " + where)
+      }
+
+      prance(where, when) {
+        IO.write("The unicorn prances in " + where + " at " + when)
+      }
+    }
+
+When you [call](method-calls.html) the `prance` method, it will select the right one based on how many arguments you pass it.
+
+**TODO: Defining operators and setters.**
+
+## Constructors
+
+**TODO**
+
+## Fields
+
+**TODO**
+
+## Metaclasses and static members
+
+**TODO**
 
 ## Inheritance
 
@@ -25,4 +77,10 @@ By default, any new class inherits from `Object`, which is the superclass from w
 
 This declares a new class `Pegasus` that inherits from `Unicorn`.
 
-**TODO metaclasses, supercalls, fields, etc.**
+The metaclass hierarchy parallels the regular class hierarchy. So, if `Pegasus` inherits from `Unicorn`, `Pegasus`'s metaclass will inherit from `Unicorn`'s metaclass. In more prosaic terms, this means that static methods are inherited and can be overridden. This includes constructors.
+
+If you *don't* want your subclass to support some static method that it's superclass has, the simplest solution is to override it and make your method error out.
+
+## Superclass method calls
+
+**TODO**