The index.php is included for client-side requests. But some aspects of apps such as their management interface would ideally not be accessible to the client. Instead we use a separate file at 'lf/apps/myfirstapp/admin.php'. Create this file and add the following content:
To view this new file, log into the Littlefoot backend at 'http://youdomain.com/littlefoot/index.php/admin' (defualt user: "admin" pass: "pass"). You should see "myfirstapp" on the left navigation under Dashboard. All apps that have an admin.php are displayed here. Click any app to manage it. If you click 'myfirstapp', you should see "Hello Admin" displayed.