Wrap your content with .avatar class to create a avatar. You have to use inline attributes to set height width of image in default avatar.

You can use class .avatar with .avatar-{sm|lg|xl} to modify size of your avatar.

Use class bg-{color-name} to change background color of your avatar.

You can add notification label to avatar by using .badge with .badge-up.

Use class .avatar-status-{online | offline | away | busy} to create avatar with status