OK just worked out how to do this. Just note though you have a limit of 2 files per posting. You click on the File Manager link at the bottom of the reply form, then Browse to the file on your computer and click Add File. It will then take a little while to upload. There is a progress bar while it uploads and then finally the file name will appear at the top of the dialog box. Then click on "Done Adding Files" and that is it. This means you no longer have to find a free file host to put your files you want here on the forum.