You can't use <vb:if... in html, only in a template. You could put your html in a template, make your widget PHP Direct Execution and use:
PHP Code:
$templater = vB_Template::create('my_template');
$output = $templater->render();
or you could use this code without making a template
PHP Code:
if (!is_member_of(vB::$vbulletin->userinfo, 16))
{
$output = "<div> This is my html
blah blah
";
}
or you could put your html in a template and