For instance, say, I add a new work item named "Develope event aggregator". I start to implement this feature and suddenly undestand that it contains more concrete tasks such as "Implement filtering by time", "Implement filtering by app name" and so on.
I need to orginize them so that there is should be a head of work items ("Develope event aggregator") and subordinated work items ("Implement filtering by time" and so on).
How to accomplish the task I descibed?
You need to use a parent child link between these work items to get a hierarchy ie tree list of items.