I'm helping somebody with similar problems in another thread from this forum, there is information in there that you can use to set your Xbox controller up. Just look at how im Telling him to configure it and compare your settings to mine in the screenshot I made and you should have no problems with it.
http://forums.dolphin-emu.org/thread-5033.html
http://forums.dolphin-emu.org/thread-5033.html
