How do I get my hair to be really straight and have volume to it ? PLzz help !?

I washed my hair then I blow dryed it. && now its puffy and I tried to flat iron it but it really wont qo how I want it and its still puffy . I want my hair to be in a nice wrap aqain. SO should I wash it aqain and just flat iron it ? Ihave school tommorow && I really need help fast . Plzzzzzz help me =( I will give anyone 10 points ! =) Jus please help , my hair is a DISASTER ! ....for anyone who answers Iwant you to know that I qreatly appreciate it. =)