Add a subscription form.
If you are adding and removing subscribers yourself (i.e., a private subscriber list), then you can skip this step. But if you want to allow anyone to subscribe to your newsletter via your web site, you can find the HTML you need by clicking on the main Help link.
Another more effective method is to simply instruct prospects to "Send any email to my list address system2thinking@cctomany.com with the word join on the subject line."
This method is more effective because it uses the prospect's own email program to send an initial message to your list address. That puts your list address into their SENT folder, making your list address known to their email program. Hopefully that will prevent future messages which come FROM that same address from going to their junk folder.