@orangepie233 : First, you needed to make sure that your Pokémon
can actually "mega-evolve". If the Pokémon has a the "mega-bubble"
icon in its profile page, like that
one.. it can mega-evolve further.
Then, you make it HOLD a "Mega Stone" item and let it reach Lv.50
or higher.. it'll mega-evolve afterwards.
You can also check out that wiki for more info on how to mega-evolve some
Pokémon on this site..
I won the "Event Spriting Contest"
as it says on News Announcement #224.