The bride's cake would transform into the modern wedding cake we know today. In the early 19th century, sugar became easier to obtain during the time when the bride's cakes became popular. The more refined and whiter sugars were still very expensive. so only wealthy families could afford to have a very pure white frosting. This display would show the wealth and social status of the family. When Queen Victoria used white icing on her cake it gained a new title, royal icing.
While I'd love to go into the many options of cake decorating, right now I don't have the time, so just a brief mention of royal icing. This is made using icing sugar and egg whites, or from a pre bought mix, and is a pipeable icing that dries very hard. It can be coloured before piping, or painted after, and is great for adding detail such as beads and borders to cake. While I used none on the poppy cake, a sprinkling of piped pearls or a bead border around the top edge can be great for covering up flaws and cracks in the icing, while enhancing the overall look of the cake.
You should use a recipe specifically designed to be a wedding cake as it will ensure that it is sturdy enough and that it makes the right amount of batter and icing. For a three-tier cake, you need to make three cakes of 12", 9" and 6", as well as a massive amount of icing. Most three-tier cake recipes have a step-by-step schedule for when you will need to bake and assemble each part.