it sounds like you have used up your available upload space.
you can either go in and delete some of your old attachments to free up space, or upgrade to a supporting membership in order to have a greater amount of upload space.
or, if you want to do something a little different, you can host the photos with a photo hosting site(photobucket, imageshack, etc) and link them to here.
here is some how to type knowledge for a hosting site: How to post a pic
And here is info to become a Supporting Member: How to become a Supporting Member