Vegetarian Nutrition must-knows?

So I'm a teen who has just recently decided to become a vegetarian. My parents think I'm doing it because they think i want to loose weight. Which isn't true because I'm doing it for the animals good. Since I'm taking all meat out of my diet and leaving in eggs and dairy (Lacto-ovo) What foods should i eat on a normal basis or what vitamins should i be sure to get to continue to grow and live healthly?