Here is a wonderful article about how to edit photos on your mobile devices using SnapSeed. I personally love the app and it is available for free in iTunes.
My most recent article is up on iPhone Photography School. I decided to do an in depth tutorial on using Snapseed for basic editing. This article only touches on about half of the features in Snapseed, but the next one will cover the rest, and will be about using Snapseed creatively.
This is aimed at the true beginner, but even if you’re familiar with Snapseed, you might pick up a few things. There are a lot of images, and even a video to help you learn.
Here is the link for the first Snapseed article.