Display Empty Properties in Inspector from a Script

Greetings all. I’ve been following along with a video series in building tiles in Unity 5 but I’m unable to actually insert soemthing because it’s not showing up in the inspector.

To show you directly what I mean, here’s the part in the video I’m following where I’m hitting the snag: Civilization/Dungeon Tile Movement & Pathfinding #2 - YouTube

All that shows up when I input a size are the individual elements, it does not allow me to place GameObjects under those elements. I already serialized the script and no search for a solution has enabled me to open up properties underneath the element.

Are my settings wrong? Do I need to do something under Debug?

the guy used an array out of either a class or struct, which in turn has the elements shown

[System.Serializable]
public struct Tiles{
public string tileName;
public GameObject tilePrefab;
}

public Tiles[] allTiles;