I think I want to go vegan . Advice?

So I have recently been trying to be mindful of what I am putting into my body. I have always struggled with anxiety, and I have surprisingly noticed that meat and dairy makes my anxiety extremely high, and causes me to just feel ... "blah"

So I have always been pretty overweight. Not obese, but nowhere near as healthy as I should be for my age. I think I want to try a vegan diet. What foods do I need to buy to make sure I get all the nutrients I need? Does anybody know of any good vegan food websites?

Thanks!