The user will only be able to use SFTP and won’t have full shell access over SSH. They will be jailed to their home directory and will have no way of breaking out of it. From the user’s perspective, their home directory is / on the server .The user needs to be able to upload files to /var/www/mywebsite

Create a group in which we will assign any user that needs to be jailed to their home directory:

groupadd sftponly

Create the user, the shell is set to /sbin/nologin to prevent ssh access.

mkdir -p /home/chroot/blake-jailed
useradd -d /home/chroot/blake-jailed -s /sbin/nologin -G sftponly blake-jailed
passwd blake-jailed

Update /etc/ssh/sshd_config

Comment out the below:

Subsystem sftp /usr/libexec/openssh/sftp-server

Add the below to the end of the file:

Subsystem     sftp   internal-sftp
         Match Group sftponly
         ChrootDirectory %h
         X11Forwarding no
         AllowTCPForwarding no
         ForceCommand internal-sftp

Restart SSH
sshd -t # This tests the configuration
service ssh restart

Configure permissions:
chmod 711 /home/chroot
chmod 755 /home/chroot/blake-jailed
chown root:root /home/chroot/blake-jailed

Create the bind mounts, there can be multiple mounts created, for this example we’re only going to use one.

Add the mount to /etc/fstab to ensure it still exists if the server is rebooted.
echo '/var/www/mywebsite /home/chroot/blake-jailed/mywebsite none bind 0 0' >> /etc/fstab

Mount the directory:
mkdir /home/chroot/blake-jailed/mywebsite
mount /home/chroot/blake-jailed/mywebsite

Test the connection:

# sftp blake-jailed@localhost
blake-jailed@localhost's password:
Connected to localhost.
sftp> pwd
Remote working directory: /
sftp> ls
mywebsite
sftp> cd mywebsite
sftp> ls -1
index.php
license.txt
readme.html
test
test.txt
wp-activate.php
wp-admin
wp-blog-header.php
wp-comments-post.php
wp-config-sample.php
wp-content
wp-cron.php
wp-includes
wp-links-opml.php
wp-load.php
wp-login.php
wp-mail.php
wp-settings.php
wp-signup.php
wp-trackback.php
xmlrpc.php
sftp> put test.txt
Uploading test.txt to /mywebsite/test.txt
test.txt                                                                                                                                                                                                100%    5     0.0KB/s   00:00
sftp> get license.txt
Fetching /mywebsite/license.txt to license.txt
/mywebsite/license.txt                                                                                                                                                                                  100%   19KB  19.5KB/s   00:00
sftp> exit

If you are unable to connect then you may want to check the logs in /var/log/[auth.log|secure]