If you find that nothing happens when you click the paperclip to upload a file after you have clicked on Go Advanced, scroll down until you come to Manage Attachments. Click on Manage Attachments. A window will open with a listing of file extensions and the size limit for each file type. At the top of the window is Upload Files from your Computer and just under that are two Bowse buttons. Click on one of them and a dialogue box will open allowing you to select a file from your computer. Select the file then click on the Upload button on the right hand side. It will appear that little or nothing is happening. Click on Submit Reply and the file that you chose from your computer should be attached to your reply.