To add a Board to your Dashboard:

Step 1: Open the Board or Kanban, press the three dots in the top right corner of your window and "Add to Dashboard".

Step 2: The pop up window will give you some options. 

You can choose whether or not to put a header on your item and choose font and icon sizes etc. 

Step 3: When you are finished, hit "Create" 

You'll see your Board on the Dashboard now, you can just click into it to access.