First make sure that you have the source for your entry. License it under some free documentation license, such as the GNU Free Documetation License that will allow ALG to use your logo.
Send an email to the ALG webmaster (firstname.lastname@example.org), telling him about yourself and your entry and ask for file attach privileges. He will give you the permission to attach image files to your forum messages. Then you can make a post to this forum with the logo images attached. Be sure to attach your source as well as the image. The text of the message should describe the entry and its license. If your entry is the best it will be used on the ALG web page.