Hi crexcrex - you can upload a pic by using the "preview" or "go advanced" button after typing in your reply. There will be a "Manage attachments" button on the next page, and you can directly upload an image if it's less than 100kb.
If you have an image hosted elsewhere and know its URL, simply click the
button above the text edit box and enter the URL in the resulting dialog box.
Welcome to the site.