Currently this is not possible, you are only able to add reports that have a chart to a dashboard. To do this:
Create a new dashboard (or edit an existing one)
Add a dashlet then select Saved Reports Chart Dashlet.
Unfortunately, there isn't a 'dashlet' adding simple rows/columns reports. If you want to add rows/columns, you have to use a List View dashlet and recreate the report using your columns/filters there.