When you create a post and add event dates to it, it
automatically gets included in the site calendar. So even if you
create a post of a different type, it could still be technically
considered an “event” in that manner, although most people use a
post type called Event as well.
Once you’ve created your event post, scroll down to the vertical
tabs and click on the one titled “Calendar dates.” In that area
you’ll see there are two options: an area for the post date,
which is handy for things like Press Releases and such, and an
area for Calendar dates. Fill in the event dates in those fields
and then save, and you will then find your event on your site’s
calendar (at /calendar), as well as on the landing page you’ve
tagged it to.