Aperture is fine, sure, though you'll likely want Photoshop for pixel editing that can't be accomplished in a raw processor. Not immediately, but eventually.
My daughter is a total beginner, and she downloaded Lightroom (at my suggestion) and figured it out pretty quickly. It's a 30 day free trial. That would be my preference (though I don't use LR personally, preferring my current workflow that uses several different applications.)