The notation tools in Mus2 are located in the toolstrip at the leb edge of the main window. The general workflow with these tools consists of first selecting the tool you need and then applying it by clicking on the score paper.
Other features such as file operations, view, layout and tuning options are available through the menu at the top of the Mus2 window. Some of these features can also be found in the toolbar just below the menu for quick access.
In the Mac version of Mus2, the menu is located outside the Mus2 window, at the top of the screen. Beside this minor difference, the Mac and Windows versions of Mus2 look and function the same.