I have tried gimp, but I like paint.net little bit better. But I am saving up for photoshop atmI've used paint.net and I would recommend it to complete beginners (say, as an upgrade from MS Paint). Personally, I own photoshop and only use it for advanced editing and effects. What I do use is a free editing program called Gimp (you can get it at gimp.org) and it is really powerful and easy to navigate. It has a bunch of features and customisation, especially for the price, and is great for the beginner all the way to professional work on a budget.