After light is a wee designed and easy to use photo editing application that offers 74 filters, 78 textures and 128 frames. Overall a well stocked application that any iPhone photographer should have.
Now you can download this app for free (normal $US1) courtesy of Apple's Apple Store iPhone or iPad app.
You can download the Apple Store App from the iTunes store (link)
Open the application
Scroll down until you see the free app offer
Click on the offer.
You will be presented with the description.
Click on download now.
You will be given a unique iTunes offer code. Just redeem it and the app will download.
That's all folks.