How to access my Facebook account on my mobile phone?

Hello,
I bought a new iPhone 6 and I try to download the Facebook app. When the app came up I logged in but instead of going back to my original Facebook accountit was as if I was creating a new one. I deleted the app and just Google Facebook. The same thing happened I logged in put in my password and my account came up but there was nothing there. No friends no pictures nothing. It was as if I was creating a new account. I know my old account is still there so how can I access it? Please help