Learning to play piano...How to play an octave?

Hey, This is not an octave but 1 more key after an octave. An octave is from c to c or a to a, ect. It is quite hard to do this so I'm thinking it must be wrong. If you go from A to B to E then it makes sense, but isn't an octave. Are these stretching exercises? I have played piano for over 40 yrs. so if you have any questions feel free to ask.