Sideboarding is a complex topic that could be the focus of an entire article, but if you have never done it before, I'll outline two simple sideboarding methods here
Build a deck, play 3 rounds, get 2 packs for playing
Throw in tricks like Role Reversal, and suddenly youre swapping resources while you fuel Zedruus steady flow of cards and life
Before we continue, lets talk a bit about supplemental sets, as it affects our discussion on the scheduling of Dragons of Tarkir
Unless you have some big-brain plan going on, though, it would be a waste since the targeted permanent wont actually be destroyed
Stoneforge Mystic I stand corrected about Steelshaper's Gift