data containers

[Moritz]

So now I have a two dimensional array ready for my classes, but sadly, I 
cant find any information on how classes can be stored in a 
multidimensional array and how I can use the instances stored there.

Ive just guessed and typed:

int add_element(ScreenElement new_element, uint layer)
{
	if(layer <= layer_count)
	{
		ScreenElement[] single_layer = layer_map[layer];
		single_layer ~= new_element;
	}
	else
	{
		writefln("cant insert ScreenElement into non existing layer");
	}
	return 0;
}

Sadly, this doesnt work, I get an Error: ArrayBoundsError upon inserting.
Can anyone tell me how this is done, and maybe even where I can find 
usful examples for more cmplex uses of arrays in D?

My biggest problem ATM is the lack of good tutorials or examples, it 
seems that D is no easy language to get started with, once you want to 
do more than basics :-(