I don't see the option below the message box...

You can't attach them. You can insert a link to a pic on the internet.

I'm trying to post a pic, and I have it on a site to host the pic, but the img tag is not showing it, only a red x. Is geocities not allowable for linking my pic?

I don't believe Geocities allows you to directly post your images on message forums. Generally, you need to find a hosting provider that allows this, and free ones are gettting pretty few and far between.

You could just post the link, I think. I pay for space on the web, so I forget the specifics of all the different image hosting sites.

-David