Under Workspace > Webmail > Settings > Sending > hover over the email identity, click the edit icon and enter the signature.

Images must be hosted on a public server e.g. your website, Flickr.com, etc.  Click the image icon and enter the address of the image to show.

Thank you very much… it helped a lot!!

I’m trying to do the same thing, but when I click on Image Icon nothing happens… no prompts.  If I paste in the flicker address to the text box it just shows the link to the photo in flicker.  Any ideas?