I was introduced to Pixlr through Instructables. Instructables ran a contest which had a Pixlr option. I am quite familiar with Photoshop and somewhat familiar with many other photo editing programs.
First go to http://www.pixlr.com
I get a lot of my clip art for FREE from Graphicsfairy
She has accumulated so many graphics over the years and they're all FREE! But most have a white background to them (what do you want for free?).
Worry no more - you do not need Photoshop to get rid of that white - use Pixlr. So download some clip art and let's go!
Once you're on Pixlr's home page, choose Open Image From Computer
and grab your image.