WARNING with picassa ....
I had it in my pc once and did not like it, so I uninstalled it, it wiped out every one of my pictures!!! I will never have them again! DUMMY me hadn't backed up my photos, so I lost them!
so if you use picassa, FIRST back up your pictures!
Another good one for amatures that I heard was good, but have never tried it, because I use both photo shop and paint shop pro, is gimp, here is a link below. Maybe google in images things made in gimp?
Gimp is FREE!!! http://www.gimp.org/
Tutorials are difficult IF you don't know your tools, so my suggestion is find a tool tut first!