how does mygui works?

hi,

i'm new to game programming. i need someone explain to me how does this mygui work. i tried to code but it doesn't show.

mGUI = new MyGUI::Gui();
mGUI->initialise(mWindow);

MyGUI::LayoutManager::getInstance().loadLayout("interface.layout");

MyGUI::ButtonPtr button = MyGUI::Gui::getInstance().findWidget<MyGUI::Button>("buttonSettings");

how does mygui work?
wat is widget, layout?
i see cegui have .scheme, so is mygui's .skin similar?

thanks.

Start from this.
http://www.ogre3d.org/wiki/index.php/MyGUI