Here are two tags which you can insert through the Quicktags menu buttons as you write or edit a post. Or just type the tags in:
More - this tag adds a
tag to your post, which puts in a â€œmoreâ€¦â€? link and puts the rest of your post on another page
Page - this tag adds a
tag to your post, which continues your post on a second page.
Notice the syntax is different than you might have seen elsewhere: they won't work if you type
I notice that the page/nextpage tag doesn't work with my custom permalinks.