Proftpd: How to "jail" specific users to different directories?

Proftpd: How to "jail" specific users to different directories?

I have a VPS with Digital Ocean and my OS is Ubuntu. I'm a beginner at
installing FTP software. I have proftpd installed on that vps with apache
on it. I want to jail specific users to different directories. In the
configuration file, I tried and only got all the users to one directory
with this:
# Use this to jail all users in their homes
DefaultRoot /var/www
Instead of getting all the users jailed to one directory such as /var/www,
I want specific users jailed to one directory such as /var/www/site1 and
other specific users jailed to another directory such as /var/www/site2.