The main overview for creating/downloading images NOT in the templates is:

lxc-create -n container_name -t container_template -- -r distro_release -a distro_architercture

An example CentOS6 is:

# lxc-create -n CentOS6 -t download -- -d centos -r 6 -a amd64

Example CentOS7:

# lxc-create -n CentOS7 -t download -- -d centos -r 7 -a amd64

Example Ubuntu 14.04LTS:

# lxc-create -n Ubuntu-14.04LTS -t ubuntu -- -r trusty -a amd64

Example Ubutu 16.04 LTS:

# lxc-create -n Ubuntu-16.04LTS -t ubuntu -- -r xenial -a amd64

Most of these containers are completely blank/fresh images.
These images do not have basic commands like 'ls' and 'cat'. To export your local path, simply run the following command:

tee -a ~/.bashrc <<EOF
export PATH=$PATH:/sbin:/bin
EOF

source ~/.bashrc

Sometimes you may forget the root password, or for some reason were not provided one at the time you created the container.
This is not an issue, you can reset the root password but locating the directory where the container is placed.
Replace <mycontainer> with your container name:

# cd /var/lib/lxc/<mycontainer>

Now we chroot to this container so we can use the binaries associated with it:

# chroot rootfs/

Once we have done this, run the passwd command to reset the root password:

# passwd

Congratulations, you can now log into the container with the root user and password you just set.
Use ctrl + D to exit out of the chroot