From the beginning, I have been using Picasa for editing all my photos (typically for adding my signature). I always wanted to move to Photoshop - but is too expensive :-( Photoshop Elements seemed to be the only option. I started looking for deals even on the PSE!!
Finally I got it f

http://www.youtube.com/results?search_query=photoshop+elements+8+tutorial&aq=1
I found the software to be quite advanced and useful.
Try it out - http://www.gimp.org/
Some help - http://www.youtube.com/results?search_query=gimp+2.6+tutorial&aq=2
Download it and play around. It is fun!
If you are intimidated by complex softwares - then Picasa is the way to go - really easy to use while being able to do most stuff about photos -
http://picasa.google.com/#utm_campaign=en&utm_source=en-ha-na-us-bk&utm_medium=ha&utm_term=picasa
Let's edit and change some faces!