Camera iPhone 5

Just bought an iPhone 5, I am new to the apple family, and live 300kms from the nearest store.  I have not been able to take a picture, am I supposed to download an app to take pictures?  I touch the camera button it comes on for a second then goes back to the menu screen and in the lock screen it opens for a second, then an apple symbol shows up and back to the lock screen!  Help!! Please!