How can we we drag and dashboard the cards in edit dashboard mode ?
If what you are asking is how does drag and drop works in edit dashboardmode ? this might help you
There are 2 ways to create a story or dashboard
1) transforming a page already containing cards into a dashboard : on the upper right corner from the wrench menu select Design Dashboard... this action will convert the whole page into a dashboard and it will make every collection containing cards, be put together in a Layout ( section similar to a power point slide in size) ,, if you have 5 collections , you will end up with 5 layouts with X amount of cards that in edit mode, you can drag and drop to re-arrange the card position in the dashboard.
2) building a dashboard from scracht: create an empty page and go to the wrench menu and select desig dashboard, at this point everything is blank but, on the right side of the dashboard in edit mode, you will see icons to drag and drop items into your dashboar... just hover over the icon to see the description of your selection such as , layout , card, image, page break , header etc
note: you can move cards from other pages into the dashboard from the card options move/copy... once done, they will show up at the very bottom of your dashboar, the appendix section where in edit mode you can drag and drop into the desire location/layout
hope this helps