Bind mounting is quite simple. Instead of mounting a block device into a particular path you are mounting one path into another path.
mount -o bind /home/andzia /ftp/andzia
You will now see this reflected when running the mount command:
mount | grep var
/home/andzia on /ftp/andzia type none (rw,bind)
If you want this to persist across reboots, you’ll just need to update your /etc/fstab with the bind mount as well.
/home/andzia /ftp/andzia none bind 0 0