There are two ways to create a Card:
From a Board
or when you are in the Explore view
Creating a Card directly in the Board
Click the "+ Card" in the middle of the screen(if you have no Cards added to the Board yet, or always visible is in the top right hand corner "+ Card".
2. Creating a Card from the Explore view
Click Explore on the left hand side in the dashboard. Now you can choose what step and what question you want to explore, see screenshot below. Now the data for that question shows in the Card with its basic setting. Now you can filter, compare and edit that Card the way you want to.
After you have the Card as you want it, click "Save" up in the right hand corner and choose what Board to save that Card to.