Add new page similar to post on both theme and admin

Hi everyone

With ghost, I can create/update/remove posts with admin access
I’d like to create a similar feature newsletter.

What I’m expecting with a newsletter is:

  • create a newsletter ( link, date, title, … ) on admin panel
  • show newsletters on theme

I can create the theme part myself but the challenging part is admin
How can I create such features on admin?