By default, b2evolution blogs are displayed using a default skin.
Readers can choose a new skin by using the skin switcher integrated in most skins.
You can change the default skin used for any blog by editing the blog parameters in the admin interface. You can also force the use of the default skin for everyone.
Otherwise, you can restrict available skins by deleting some of them from the /blogs/skins folder. You can also create new skins by duplicating, renaming and customizing any existing skin folder.
To start customizing a skin, open its ‘_main.php‘ file in an editor and read the comments in there. And, of course, read the manual on evoSkins!