Button/s not doing as expected

I am very new to Android Studio and I am learning as I go. a Friend of mine asked me to help develop a "Time and attendance" app for him. I got the first activity done, but now with the second activity, I am stuck on some of the buttons.

I have a "back arrow" button and a "send button". The "back arrow" button is working, but with warnings:

1. Function "onBackArrowClick" is never used
2. Parameter 'view' is never used

The "send button" navigates back to the main activity when clicked which should do the following:

1. generate a random verification code and send the code to the email address entered into the email input field.
2. it should also start a timer that counts down

I assume that there is something wrong with the "view" parameter I am using for the "onClick".

Is there something I need to provide so you can understand better?