It’s not hard to find images to use online – just use an image search. This works well, but it’s worth noting that doing so isn’t necessarily legal. Most of the images you can find this way are owned by their original creators. This likely doesn’t matter if you’re only using something for private use, or even a school assignment, but if you intend to publish a work you need to make sure all rights are cleared.
To download the clip art and animated GIFs on this site, just move your mouse over an image or animation and right-click. Then select "Save Picture As..." (or "Save Image As" if you're using a Mac). Feel free to open the pictures in your favorite graphics software, such as Photoshop, Fireworks, Gimp, etc... and edit if you wish. Keep in mind that linking to these images is not permitted.
My school district doesn't allow students to access anything except Google; therefore, clipart is useless. More and more school districts and companies are blocking applications and websites to prevent access to inappropriate images and content. My first and second graders have always loved doing PowerPoints; however, with clipart no longer working, they cannot do these projects any longer. Older students access Google images to get graphics for their projects.