I'll need to know how you access TriumphRat.Net, what you see in the URL field in your browser. If you know how, email me a screenshot of your computer desktop when you're browsing TriumphRat.net (webmaster@triumphrat.net).
If you wish to try again, close/re-open your browser and go directly to the TriumphRat.Net home page:
http://www.triumphrat.net
Then follow the Classifieds Link from the main menu and try uploading your ad again.
The error message is common from someone trying to add content to this site, from another site (domain). It isn't allowed.