I recently designed and ordered my first batch of PCB's (first ive ever created) They were great except for one thing; I thought that setting my SMD pads layer to 'All' in the software would create a pad which was accessible to all PCB layers. The pad was created on both layers but was not electrically connected. So my question is: what is the standard way of allowing an SMD pad to be accessible from multiple layers? Would it just be to use a via? Many thanks.
Surface mount device (SMD) pads, are, well, on the surface. Since the point of these pads is to connect to the device, it makes no sense to have these pads on inner layers the device can't possibly touch.
What you are apparently asking about is how to make connections between different copper layers of a board. That is done with special plated holes called vias. A via is a hole in the board, but the inside is plated with copper, and traces from each layer can connect to this plating. Vias connect all the traces that touch them from all the different layers.
You seem to be confusing SMD pads and thru hole pads. Since thru hole pads are for connecting to a pin of a device that extends thru the board, they are made much like vias. You can think of a thru hole pad as a pad and a via all in one.
One of several reasons we don't like thru hole devices is because the pads interfere with all the layers. This puts more constraint on routing and requires more space as a result.
With SMD, you don't have this problem. All the connections to the devices are on top (or sometimes also on the bottom) layer. During placement, you try to minimize the distances between connections and the cross-overs. You then use vias only when you need to switch layers. You can run unrelated signals right under device pads on other layers.