Don't know about Dreamweaver and the other MX overload.
But plain HTML: Create a form with an <Input>-tag and a button to send the content. Easiest you send the content via an e-mail to your newsletter service (typically TO:
newletter-subscribe@xyzdomain.com or To:
newsletter@xyzdomain.com + subject: subsribe). With a little JavaScript you can even check for a valid e-mail address pattern and send it in the right form.
Ask your newsletter provider for an HTML template and cut and paste it into you source. Adjust according to your liking with colors, etc. Test after each little change if it still works, so you don't destroy the integrity of the template.
Good luck
K<o>