Jim, first resize your pic to be less than 700 x 700 pixels and the pic is within the byte size (I think it is 80 kbytes). Then you will see at the bottom of your post (reply to post), where is says "Attach a File", to the right is a "browse" button. Select the "BROWSE" and select the pic that you want to post on your C drive. This function will upload your pic to RCUniverse's server, and it will appear as a thumbnail.
Hope that his helps you out.
Kevin