My iPod Touch won't let me get onto the Facebook ap and I have Wifi. what should I do?

I just got an Ipod Touch and i have wifi and internet connection and i downloaded the facebook app and when I try to log in it wont let me. I know the internet works because I've gotten on google. And i know that im putting in the correct login info. because ive tried it out on my computer. What should I do?!?