what I do is just use the open file option in the "file" menu in the top left. you will need to search your computers hard drive for the files location before being able to do it. I will try get some pictures up to help make it easier, what I do when I save pics from the net is I actually have a file designated in "my documents" just for pictures of bonsai, this makes all the pictures easy to locate and allows paint.net to open them easy!
good luck
taking the top half of trees of since 2005! 
...all good now.
