Click go advanced, then click manage attachments. Then an popup is opened, where 5 empty places with buttons next to it are. Click one of the buttons, preferably the top one, and browse in the window that comes up to the folder where you have stored your replays, and double click the one you want. Do the same with the other four buttons, and click upload. Wait for it to refresh, and close the popup. Now type your message like you would normally, and click post reply. Tadah, you have posted your replays