Newsletter creation documentation

I want some documentation on the creation of a newsletter using the newsletter page on the popup builder. It has some shortcodes in the sidebar, like [first Name] etc and I was hoping that when I put them into the newsletter, the first names of the subscribers I sent the newsletter to would appear in their copy of the newsletter, but all they get is [first name]. I can find no documentation anywhere about creating newsletters. I don’t want to know about creating the form, I have done that, I want to know about creating the newsletter.

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