How to put a self-reference table into hierarchical objects

Note! this is a question focussed on the data transfer between Data Layer and Business Logic Layer. 
So NO Presentation  Layer kind of answers!

I have a self-referenced datatable, with columns:

GroupID
GroupName
Parent

How do I fill a hierachical object named "Group", with the records from this datatable.

I have to make some kind of loop to analyse the records in the datatable, but do not know where to start.

Who can help?
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