After you have downloaded the widget from MuseFree.com double-click on the file.
.Muse files will open in Muse document. You can modify, copy and paste into your project.
.Mulib files will be added to your library panel. If you don’t see the library panel on the right hand side, go to the top menu and click on Window > Library. The widget will be in MuseFree.com folder. Drag it into Muse document.