The software that came with your camera, and any photo-editing software should have the option of resizing and reducing resolution. Both result in smaller file sizes.
http://www.quiltingboard.com/posts/list/429.page is where the guidelines are. Basic rules are file size less than 1mb, and no more than 800 pixels either in width or height. Also, it should be jpg format to show up. If you get stuck, pm me and I will find an online site to resize them.