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A newly created dashboard will be empty by default. To add widgets click the 
in the bottom left corner. This will set put your dashboard in edit mode. Press the 'Add new widget' section in the middle of the page or the 
in the bottom left corner to add a new widget. A menu will appear on the left side of the screen.
From the drop-down menu on the top different kinds of widget bundles can be selected. You can play around try different kind of widgets. They mostly work in the same way. For now we select a 'Charts' and then click the one on the top called 'State Chart'.
A menu which looks like the this should now appear.
It is now time to add a data source to our widget. Click the 
'+ADD' button to select data sources.
Under the type section you either chose 'Entity' to select a device, or 'Function' to write your own function to visualize data. An example of a function is a sine wave.
For now we select 'Entity'. Here you can name the entity whatever you like, in this example we will name it 'Sulafjorden Wave'.
Once entered, a message will appear saying that no entity was found, press the 'Create a new one!' hyperlink.
From the window that appears chose 'Single entity', 'Device' and then finally select the 'E39_A_Sulafjorden_wave' device from the drop down menu. Finnish by clicking the 'ADD' button.
Clicking the 'Timeseries' section will now prompt a list to appear. The list contains variables collected from the Sulafjorden buoy. Looking at the data section we can learn more about what the variables represent.
Select 'Hm0' which is described as "Significant wave height estimate from spectrum".
It should now look like this.
To add more variables from the same entity, simply click the 'Timeseries' again. Now select 'thmax', which is described as "Period of highest individual wave from zero crossing analysis".
Once completed, hit the 'ADD' button at the bottom of the window. This should create a chart widget at the dashboard with two variables plotted.
To finalize the dashboard click 
'Apply Changes' at the bottom right.
You can add multiple entities and compare data from different sources in the same widget. It is also possible to change the color and look of the widget. This can be done under the 'Settings' tab for the widget.