Laravel Add a new column to existing table in a migration

I can’t figure out how to add a new column to my existing database table using the Laravel framework.

I tried to edit the migration file using…

<?php

public function up()
{
    Schema::create('users', function ($table) {
        $table->integer("paid");
    });
}

In terminal, I execute php artisan migrate:install and migrate.

How do I add new columns?