magento1.9 get login event with observer

Question

I'm trying to use observers
My goal is to do something after successful login
I wrote this but I think I don't understand something...
What's wrong?

app/etc/modules/Drg_Customeraccess.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Drg_Customeraccess>
            <active>true</active>
            <codePool>local</codePool>
        </Drg_Customeraccess>
    </modules>
</config>

app/code/local/Drg/Customeraccess/etc/config.xml

   <?xml version="1.0"?>
<customer_login>
    <observers>
        <Drg_Customeraccess>
            <type>model</type>
            <class>Drg_Customeraccess/observer</class>
            <method>customerLogin</method>
        </Drg_Customeraccess>
    </observers>
</customer_login>

app/code/local/Drg/Customeraccess/Model/observer.php

<?php
class Drg_Customeraccess_Model_Observer
{
    public function customerLogin($observer)
    {
        $customer = $observer->getCustomer();
        if ($customer){
        echo "nameOBS-".$customer->getFirstname();
        }


    }
}
?>

Thank you

Answer 1

app/code/local/Drg/Customeraccess/etc/config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Drg_Customeraccess>
            <version>0.1.0</version>
        </Drg_Customeraccess>
    </modules>
    <global>
        <models>
            <drg_customeraccess>
                <class>Drg_Customeraccess_Model</class>
            </drg_customeraccess>
        </models>
    </global>
    <frontend>
        <events>
            <customer_login>
                <observers>
                    <drg_customeraccess_login>
                        <type>singleton</type>
                        <class>drg_customeraccess/observer</class>
                        <method>customerLogin</method>
                    </drg_customeraccess_login>
                </observers>
            </customer_login>
        </events>
    </frontend>
</config>

app/code/local/Drg/Customeraccess/Model/Observer.php

<?php
class Drg_Customeraccess_Model_Observer extends Varien_Event_Observer
{
    public function customerLogin($observer)
    {
        $customer = $observer->getEvent()->getCustomer();
        if ($customer)
        {
            echo "nameOBS-".$customer->getFirstname();
        }
    }
}
?>