Who are you?
Before we begin there are some things that would be useful to know if you wish to avoid the possibility of some slight confusion. First, Princess Celestia hasn't been the only alicorn ruler. In fact, there have been multiple before her and Princess Luna, all ruling at separate times before Discord's temporary rule of chaos. Second, alicorns are not born with all their knowledge of flight and magic and must therefore learn it from somewhere. Most of said knowledge is conveniently located in the Canterlot Archives. However, some of that knowledge is best taught through face-to-face interaction and spoken words instead of through text. Lastly, Discord has not always been the way he is now, and I do not just mean that he hasn't always been encased in marble. Good, know that we have that out of the way we can continue on fairly uninterrupted.