Select the color you want and click on a region on the map. Right-click on it to remove its color or hide it. Advanced...
Hold Ctrl and move your mouse over the map to quickly color several regions. Holding Ctrl + Shift has the opposite result.
Add the title you want for the map's legend and choose a label for each color group. Change the color for all regions in a group by clicking on it.
Drag the legend on the map to set its position or resize it. Use legend options to customize its color, font, and more.