How to get my hair straight?

I have short choppy layers in my hair. My hair is naturally curly and it makes my hair look horrible. The layers curl inwards and some outwards. The top layer looks the worst. It's really hard to straighten. When I get to the top layer it won't straighten. When i finally get it to, it poofs out and the ends flip up. I can't get it any better. I shampoo and condition. How do I get my hair to straighten? Please help.