>>31
It depends on what you need.
The default markup is:
'''text''' -> <b>text</b>
''text'' -> <i>text</i>
text -> <spoiler>text</spoiler>

TB+vichan-devel also adds this one by default:
==text== -> <h2>text</h2>

If you want to add your custom markup, then you need to add a line to your inc/instance-config.php like this:

$config['markup'][] = array("/\\(.+?)\\/", "<span class=\"spoiler\">\$1</span>");

The first string is a regular expression. Here you can find the documentation about those: http://pl1.php.net/manual/en/pcre.pattern.php