vBulletin Manual - Adding a Single Avatar

To add a single avatar enter the following details and click the Add Avatars button:

Title - enter the name or title you want to apply to the avatar. This will be the title of the image that is displayed in the Avatar Options in the User Control Panel
Minimum Posts - enter the minimum number of posts a member needs before they are entitled to use this avatar. If you want to make this avatar available to all users, enter 0 or leave blank
Avatar File Path - this can either be an URL of an image (e.g. http://www.example.com/images/avatar.gif) or a path on your web server (e.g. "/www/sites/htdocs/images/avatar.gif").
Avatar Category - select the category you want to assign the avatar to
Display Order - This determines the order in which the avatars are shown. By default the next display order is assigned and can be changed at a later date.