You can use an online editor, like the Gifworks.com, select File/Open an Image, and then Browse for the imahge on your hard drive, and Upload it. You can resize or crop it (In Edit), or reduce colors (in Optimize) to make the file size smaller. And it's free!

About your avatar (one of Louisa Agis's?)... AW displays the smaller images of jpg-files as gray blur, and it's a server issue, and not anything we can do for now, except to change it to gif, or png. I guess anyone who has graphic software could do it for you, but I think you need to ask Louisa permission first (she might even change it for you).