Create a cohort and run a Cohort Analysis report in Analysis Workspace.
These metrics group your users into a granularity buckets, based on an activity (such as placing an order).
The time granularity of Day, Week, Month, Quarter, or Year.
The metric that places a user in a cohort. For example, if the inclusion metric is Orders, only users who placed an order during the time range of the cohort analysis will be included in the initial cohorts.
The metric that indicates the user has been retained. For example, if the return metric is Video Views, only users who viewed videos during subsequent time periods (after the period in which they were added to a cohort) will be represented as retained. Another metric that quantifies retention is Visits.
The report shows visitors who placed an order (Included column), and who returned to your site in subsequent visits. The reduction in visits over time enables you to spot problems and take action.
Select cells (contiguous or noncontiguous), then right-click > Create Segment From Selection.
This example segment would show all the visitors in January 2015, month 1 and 2.
The saved segment is available for use in the Segment panel in Analysis Workspace.