During initial installation, Structure plugin has created an empty, default Global Structure. You can decide to use only that single structure, or you can create as many structures as needed. To create a new structure, use Structure | Create Structure menu.
A structure is a "container" for issues — it is initially empty, and someone needs to put issues into it and arrange them in a hierarchy. This can be done manually, issue by issue, or automatically with an Import function or a synchronizer.
To create a sub-issue, select the issue in a structure and click +Sub-Issue button.
To make structure always contain issues that satisfy a certain JQL filter, install a Filter Synchronizer — open Structure | Manage Structures page, locate your structure, click Settings in the Sync With column, and install a Filter synchronizer.
Structure is integrated with JIRA Agile (GreenHopper) — the issue details panel on the Agile board shows the position of that issue in structure. You can install JIRA Agile (GreenHopper) Synchronizer to maintain a structure with Theme-Epic-Story-Task hierarchy, or to synchronize backlog/sprint rank with the position of issues in a structure.
Getting Started - Walkthrough
Open Structure | Manage Structure menu and click Create Structure. Create your own private structure to play with.
On the Manage Structure page, click on your structure name to go to the Structure Board.
On the Structure Board, click Search, then click JQL and type assignee=currentUser() order by updated. You can use any other query - see more about Searching and Filtering.
When some issues are found by the search, click "More Issues in JIRA" button if it's not switched on, and then drag-and-drop several found issues into the Structure.
When you have several issues added to the structure, try to rearrange them to create a hierarchy. Hold Shift and drag issues up and down or left and right to place them at a different position in the hierarchy. You can also drag by the drag handle at the left side. See Using Drag and Drop to learn more.
Use keyboard arrows to navigate structure or Ctrl+Arrow to move issues up/down or indent/unindent.