Hi,
So started kits can be really neat to get you going, especially on tools. From what I have seen they don't usually have the materials to really make anything specific (granted there are a LOT of different materials). The duck feathers are often used in classic fly wings on dry flies (if they are from the wing, if they are Cul De Canard feathers they are used for emergers mostly). Deer fur is also a wing and a tail material typically for dries. Peacock herls are used a lot, often toward the head of the fly. The Prince Nymph is the most notorious for using peacock herl, and this fly can be tied in various colors and styles. My biggest recommendation to you is to check what flies are used where you like to fish, then find the right materials to tie them. If you want a great place to go to learn to tie, I really enjoy Tightline Productions on Vimeo (https://vimeo.com/user3412872).
Happy Tying!
T
