How do I tier wedding cakes

Yes, that really is the Sydney Opera House in the background. These cakes all have multiple tiers. They are doubled up so you actually have 4 cakes inside. The point is that they look more modern because they are not separated by the plastic pillars. Without going into great detail, cover your cake or cakes joined together making sure each tier has a seperator board under it and internal pillars inside it for support. Cover the cakes with icing and assemble with the supports. Cover the join with a ribbon, piping or decorative bits. Let it set before moving it.
For more detailed instructions my friend Karen Hill of Wedding Cake Art Sydney has classes. She can design a cake for your individual needs as well.