well im asking, but ill also just try it. edit, ok it didnt work but copy pasting might not be the way to do it hmm
Use the Manage Attachments button on the page where you post....it's just below those three check boxes...it's easy. You just upload it from your computer or somewhere online.
On the page where you write whatever you're posting, scroll down below the submit reply button, past Miscellaneous Options, and you will see a button that says "manage attachments." Click on it, and you can upload files directly to the thread, just like you do in the galleries.