Managing Your Dashboard
This article describes how to edit a Dashboard, including on how to assign and arrange Widgets for that Dashboard.
Editing Your Dashboard
Go to the main Dashboards page, which can be found in the top menu via "Dashboard" -> "Dashboards". Once loaded, you'll notice a grid in the first tab that holds (most likely) one dashboard, the "Default" dashboard. Right-click the row, and click "Update Dashboard". This will load the editing page for the Dashboard.
You will see a name and description field, and below, a grid of Widgets assigned to the dashboard. You can drag the widgets around to rearrange them, add widgets by clicking the "Place Widget" button, or remove widgets by right-clicking on a widget: