C#: Get a class to appear in the editor

Hello,

In C#, how do you get a custom made class to appear in the editor? For example, I am trying the following:

using UnityEngine;
using System.Collections;

public class Platform
{
    public GameObject prefab;
    public float probability;
}

public class PlatformController : MonoBehaviour {
    public Platform[] levelPlatforms;

    ...
}

However I can't assign any values to Platform from within the editor. In Javascript I can achieve this by:

class Platform {
   var prefab : GameObject;
   var score : float;
} 
public var levelPlatforms : Platform[];
...

I also tried to make Platform a struct but that didn't make a difference.

Thank you,

Justin

http://unity3d.com/support/documentation/ScriptReference/Serializable.html