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.