problem with installing apps on my new iphone 3G

[ksabek]

hello 2day i got a new iphone 3g fully unlocked, but ive been trying to install apps on it and i downloaded the facebook app from itunes but when syncing it says the app couldnt be installed on this iphone!!!!
wut does this mean?!!!
i even tried through the app store on the phone n same problem...what should i do?!!!

 

[Opie]

Do you have an itunes account with your email and a credit card?