The next stage of the process is to download metamask.
You will have to have this downloaded to be able to receive your funds from your mobile app and then forward them onto your trading platform which you will register next.
This download will provide the bridge between step 1 (trading platform) and step 2 (Coinbase app)
You will have full control and privacy of your account.
Please ensure that you have a pen and paper ready whenever you create an account. Ensure to make a copy of your password and account details so that you can always gain access and place them in a secure location as you may need those details to log into your account.