Take a look at
http://www.wowwiki.com/Using_the_Int...s_Addons_panel
That will allow you to create the panel of which you can create widgets to sit on top.
All documentation can be found here
http://www.wowwiki.com/Widget_API
You could also take a look at
Portfolio or AceConfig, as they are supposed to make the process of creating options "easier" (although I wouldn't personally advise using them, as there is more to gain doing it manually).