vBulletin Manual - Implementing Avatars on vBulletin

The administrator can choose to implement avatars a number of ways, they can opt to disable avatars completely, allow users to select from a list of predefined avatars or allow users to upload their own custom avatars. The administrator can assign the avatar permissions on a per-usergroup basis.

To configure avatars on your bulletin board first open the vBulletin Options menu in the Admin CP. Select User Picture Options.

In this section you can set the following options:

Avatars Enabled - Use this to enable/disable the overall use of avatars
Avatar Display Width - This option defines the number of columns of avatars displayed to the user via the user control panel avatar selection page.
Avatars Per-Page - This option defines the number of pages the avatars will be displayed over in the user control panel avatar selection page.
Profile Pictures Enabled - This option relates to the use of profile pictures which if enabled will allow members to upload small images, usually larger than avatars, that can be displayed on the member's profile in the members' list.

If avatars are enabled the administrator can also choose to include avatars in the registration options. This will set the defaults for new members during the registration process.

To enable avatars for member registrations:
AdminCP > vBulletin Options > User Registration Options > Default Registration Options > Display Avatars > Tick the box