The Managing Sandboxes option can be accessed using the dropdown arrow in the Org section (top status bar).
Selecting this option will bring up a screen containing a list of Sandboxes. You may add or remove sandboxes using the controls in this screen.
To Add a Sandbox, press the Add Sandbox button. This will bring up the dialogue window.
From here select any Sandbox in your organization and the Confirm button to continue.
Note: Your Salesforce user profile has to have "Manage Sandboxes" permission in order to be able to search sandboxes by name. You are still able to add a sandbox by entering its ID if you don't have this permission.
Refresh or Move Sandboxes
If you have recently refreshed your Sandbox, Salesforce will change the Sandbox ORG ID. This will result in the updated Sandbox appearing as a DataGroomr Trial. To resolve this, click Move Sandbox on the Sandboxes page, choose the freshly-minted sandbox. After confirmation, DataGroomr re-points every reference behind the scenes to the new Sandbox.