Just an fyi, I never click on random links posted, as even if they're self explanatory, you should at least tell me why I should be spending time looking for it. Even if you just say 'hey I like this guide,' it looks less like you searched for a guide on leaguecraft, clicked the first one, and posted the link. There's also not even a cool video like lmgtfy.

Annie's an extremely powerful mid-game mage, so you have to know how to capitalize on her strengths - extremely high burst levels 6-11, and good initiation with AoE stun. A good build, I find, is Amplifying Tome, Boots + Ruby Crystal, Haunting Guise + Sorcerer's Boots, Rabadon's. This gives you a strong early game and an amazing mid-game.

For summoner spells, take Ignite + Flash. If you don't like Ignite, you don't have to take it, but always, always take Flash. A good Flash + Tibbers initiation wins games.

As for Pyromania stacks... the way I play is, levels 1-5 I don't even count them unless I want to harass my opponent (charged Q --> W will deal more damage than most people expect). Levels 6-11, if I'm charged and I can't wait any longer, I'll blow as quickly as possible through charges 1-3, and stay no lower than 4, so that in an emergency I can go E-W and drop a stun with Q or R. If a teamfight is going to start soon, always, always conserve your stacks. Like I said above, a good Tibbers initiation wins games.