I want to straighten my hair, without using any hair products that change appearance, such as sprays.?

Im 15 and a guy, and I just wanna straighten my hair a little. My hair is curly, the type of curly that when left too long makes an affro, I think it looks like the Jonas bro with the curly hair, but maybe curlier. I dont like it short, I just want it to be a little wavier instead of piling up tall. Any tips? maybe a shampoo or conditioner, ways to dry hair? Something easy.