So when you start your os you will see no dashboard there don’t panic it is disabled by default.
Just go to System Preference -> Mission Control you will see off beside Dashboard. From the drop down menu you can choose either As Space or As overlay. As Space is the old way to show the dashboard so an extra desktop screen will be added in the left most side. As overlay means it will appear as overlay so you can use either keyboard shortcut or hot corners which you can choose by clicking the button Hot Corners. When you will hover your mouse pointer in the hot corners the dashboard will appear.