Having problems with certificate in workflow email - the image does not show and how to add the names

I am having problems figuring out how to get the image to show in the email, how can they print just the certificate and how do you get the embedded data with their names to show up on the certificate?  I have the workflow with this information typed out but others are worried that anybody can changed the wording so asked if I can add a real certificate to the email instead.  I need to figure this out by Monday, August 19th since it will go live then.