Just below the last reply in this discussion, is a blue bar with the PAGE selector in it (Page << <prev 1 2 3 etc). Just below that bar on the far left, it says POST REPLY. If you pick POST REPLY, you will see a new window to enter your reply, and it has the file upload option. That option is not available when replying in the FAST REPLY window. Also, when you upload, you will not see your pictures until you OK the reply and it gets added to the thread!