To Create a New DGN Tree

From the Items dialog icon bar, click the Open Tree Manager icon.

The Tree Manager dialog opens.
In the Tree Manager dialog, click New and select DGN from the drop-down list.
The Open a Repository dialog opens.
Select a repository from the Location list or click the Browse button next to the field.
Using the remaining fields in the Open a Repository dialog, configure the new tree.
Click Open.
The new entry appears in the tree pane of the Tree Manager.
(Optional) The tree name now is in an editable state, so you can rename the tree.
Use the remaining Tree Manager dialog options to define the content, and/or display options of the new tree.

Tip: For the new tree to appear in the Items dialog, you must enable the check box next to its name in the tree pane.
After configuring the display options, click Apply to save the changes.
The new tree appears in the Items dialog as configured.
Click Close to return to the Items dialog.