Modification in PostRegister Action Method - Laravel 5.1

I am using inbuilt Authentication System in laravel 5.1. I am trying to modify the PostRegister Action Method.

We can find the code in below mentioned path.

vendor\laravel\framework\src\Illuminate\Foundation\Auth\RegistersUsers.php

Can you suggest where should I do the modicications if I have to add one more field in User Table. I have already updated the migration file and database is updated also.

via Chebli Mohamed