Tim.. are you getting a msg saying the file is too big, if so, you have to resize the picture smaller using a photo editor.
To load the picture just click on the browse button below this window, find your picture in your file and either double click or click the open button, which will put the path in the box below..then hit update & preview button below, once the picture is loaded into the preview window with your message you can click "post this to discuss-o-mat"