Can anyone tell me how to make optgroups appear in sublists instead of in the same list? 
can you tell me which opt-in plugin or software you are using in your website? please provide me more details, so I can fix it.
They do that by default, at least in some browsers—if I understand you rightly. What browser are you using?
Hii ralph.m,
I am using IE9…
OK, I must be misunderstanding what you are asking. Like other browsers, IE9 indents the items within each optgroup and emboldens the optgroup’s heading.