BuddyPress.org

I have been looking for a tutorial to create a buddypress menu. it’s just like here, buddypress.org. ( http://prntscr.com/fmxou7 )

It seems that it uses wordpress admin bar menu. I know how to remove, add, modify wp admin bar.
But I can’t really get it to bring front-end like this site.
Maybe you need to put it into a memory and call again. then it won’t hurt the origianl wp admin bar. But I can’t really get started.

Is there any tips for it?

Thank you,