com posar un doble punt a una blanca.

"... how to add a double augmentation dot to a white note (half-note / minim)?"

1. Enter the half-note / minim on your score.
2. From the toolbar, use the icon for double augmentation dot (shown as a double-dotted quarter-note / crotchet).
3. If the double augmentation dot is not visible on your toolbar, use the Customise toolbar gearwheel to make double augmentation dot visible (by opening the "eye" symbol).