Because newsletter templates are available in all variety of lengths and sizes, there is really no limit to the content that you could potentially write. Keep in mind, however, that you should probably keep down your word count to a level that people are comfortable reading. While you may think everything that you are spouting off is fascinating, it's helpful to first sit down and make an outline of what you want your main message to be, or what the major news is that you are trying to share.
What is the initial process and how do you get your hands on WordPress in order to create your own website templates? You will need to go to WordPress.org and download a version in the language of your choice. You then extract the zip folder into the root of your site, and you will see tons of files pop up. Don't worry about opening those or going into them as what you need to work with will be significantly small. Then go to yoursite.com/wp_admin/ and you will go through the simple installation process which is basically just WordPress hooking itself up to a database which it creates in your server in order to work. That's all there is then you can start rolling.