These steps are assuming that you have already opened the New Thread or New Reply page, and have typed what you want to appear in the body of the thread.
1. Scroll down from the "Message" box in which you were typing, past the "Submit Thread" and "Preview Post" buttons.
2. Click the button labeled Manage Attachments. (You may have to disable your pop-up blocker)
3. The Manage Attachments window should now pop up. You may either:
- Click Browse... to navigate to a file on your computer, press OK, and then press Upload.
- Paste or type the URL of the file on the Internet that you are trying to attach, and press Upload.
4. After the file has uploaded, scroll past the table of file extensions, and click Close this window.
5. Continue editing your new thread or reply, and when finished, submit your post.