IF you just want to resize the images, and don't really care about using a software, this is a quick and dirty online solution you should Resize Images online
In a pinch MS Paint works too, but it's no frills (or minimal frills) (And of course you need to download the images to your PC first)
EDIT: Some hosting sites Photobucket for example have image tools includes, and are a good place to host your picture files if you like manipulating them.