The first principle to learn will be the center line theory. You should imagine a line going straight down yourself, as well as your opponent. The idea is to guard your own center line while simultaneously attacking your opponent’s center line thus taking the fight to them.
There is much more to learn about the center line theory however, I am not trying to be the top source or ultimate guardian of all things wing chun. I am an enthusiast and I have a huge amount of respect and admiration for the art. That said, here is a link to a really great article discussing the center line theory in depth.
There are 3 sets or forms in wing chun and they are “Sil Lim Tao” (or Siu-Nim-Tao), “Cham Kiu” and “Biu Tze”. In the beginning you should just focus on Sil Lim Tao or “small idea” and understanding the center line theory.
There is so much more to learn but there is no need to risk information overload. In between practicing your first form you can take the time to maybe study some wing chun lore and history. There is a bit of back and forth about whether wing chun was first mastered by a woman.