"when I try save to PDF it just wants to save it to a file?"
Correct. The difference between "Mail PDF" and "Save PDF" is that the first opens a new Mail message with the file attached. the second saves a file which you may attach to an email message.
"Terrainathome is a good example of what I am trying to do."
Not familiar with Terrainathome, but my guess is that the company is sending an email message containing HTML code that downloads what's essentially a web page into the displayed message. To do that, you'll need a website, software that will produce the necessary HTML code, and recipients with email clients capable of interpreting HTML (which is 'most email clients' these days).
Regards,
Barry