Obconf doesn't help with changing the Openbox menus. I noticed that myself. It does give you a nice way to select the theme/fonts/etc. if you find what you get out of the box hard to read or look at.
I have seen some tools, usually written in an interpreted language like python, for setting up menus in Openbox (and other window managers). Openbox's settings files are all in XML, so personally, I prefer to open in a text editor and edit menus and keymappings by hand. It's stricter in syntax than editing Fluxbox files by hand in an editor, but still can be done. You'll find the files under .config/openbox in your home directory. My personal preference it to edit XML by hand rather than using a program to generate, but that's just my preference. As mentioned, there are tools to do it the other way. You can probably check the Openbox site or Sourceforge for them if you're interested in finding them.