I'll try to help you decide from some of what has already been suggested (and add a further suggestion as well):
Hc4361's post refers to uploading pictures to the 'Picasaweb' galleries. You can use the Picasa software to edit images on your PC without any need to upload them at all.
The Picasa software is widely praised and easy to get to grips with.
Irfanview, as recommended by 4candles, is an excellent picture viewing program (which deserves a place on everyone's PC), with some useful editing facilities as well - but it still wouldn't be my first choice as an image editor.
Gimp, as recommended by D97x7, is an open source (i.e. free!) program which is close to the full versions of Photoshop (which is used by professional photographers, advertising companies, magazine photo editors, etc). It's a superb program but (because it has so much to offer) there's quite a steep learning curve involved if you're to get the best from it. (If you decide to download it I STRONGLY advise downloading the documentation as well!).
Serif PhotoPlus Starter Edition is a 'light' version of an excellent full commercial program, which offers a great deal to the 'casual' home user:
http://www.serif.com/...ware/?MC=FSSPHOTOPLUS
Chris