vBulletin Manual - The Style Manager

The Style Manager is the central hub for editing and creating vBulletin styles and their constituents. From here you can control every aspect of the way your vBulletin installation appears to your visitors, from simple color and font changes right through to fundamentally altering the layout of the board by editing templates.

The image above shows the Style Manager as it would appear immediately after a new vBulletin installation. Looking at the Style Manager from left to right, various controls are visible.

The 'Allow User Selection' Checkbox
This checkbox controls whether or not the style will be available for non-administrators to use. If the checkbox for a style is cleared, only administrators will be able to use that style.
The Style Title Hyperlink
The style title is also a hyperlink. Clicking it will open a new window and show the public area of your vBulletin using the style you clicked, even if the public are not able to use that particular style.
The Display Order Text Box
The small text box containing a number controls the display order of a style. Higher numbers will be displayed later in the listing. This value makes absolutely no difference to the content of the style, and is used soley for convenience of display.
The Style Options Menu
This popup menu contains links to make alterations to the style such as changing its title, downloading the style as a style.xml file etc.
The Expand/Collapse Templates List Button
Clicking the [« »] button will open or close the list of templates for the current style.

Note:

Examples of (modified) vBulletin boards: https://www.vBulletin.com/links.php
Examples of vBulletin style and template modifications here: https://www.vBulletin.org/forum/