I think where you are going wrong is you are doing something with the handbrake, there is no need, once set up you need never touch it again. Make sure both are engaged and when you stop it'll engage and when you go to pull away it will switch off. You'll see the handbrake light will be green on the dash when you stop at a junction etc and will go red when you park up. Have a look at your handbook and familiarise yourself. As I said before, if it's all set up correctly you shouldn't even need to think about it let alone do anything.