can i actually use a pointer on a class? it's been so long since i used classes.
Yes, you can use a pointer on pretty much anything that has a memory address.

Your code has a lot of mistakes, layer_nodes is a pointer to neural node, and you are treating it as a 2D array, which is a pointer to a pointer. Also, when creating a dynamic array, the only constructor you can call is the default constructor(which must explicitly be present).

Also, when allocating dynamic memory, make sure you free it once your done.

Here is another way you can achieve what you were trying to do..

Code:
class neural_node{
    public:
		neural_node(){ }

		void set_size(int size) {
            node_size = size; 
        }
    private:
        int node_size;
};

class layer{
    public:
        layer(int node_size, int number_of_nodes){
            layer_nodes = new neural_node[number_of_nodes];
			for(int i = 0; i < number_of_nodes; ++i)
				layer_nodes[i].set_size(node_size);
        }
        ~layer()
	{
		delete[] layer_nodes;
	}
    private:
        neural_node* layer_nodes;
};