The Properties panel will open on the right side of the Stage. In the Organization section is a setting, "Is a Baseline:" (You may need to scroll to see this setting.) Select the checkbox for Is a Baseline.
The Properties panel will close. To use the Baseline to start a new project, select the New Project quicklink in the upper left corner.
On the New Project From Baseline panel, rename the project. For this exercise, select the name field and we'll add a name.
Selecting Keep Asignments will mean that any authors or reviewers assigned to the original Baseline will be assigned to the new project. Select Duplicate Project.