You can add a Task ID to a Test Case, Test Suite or Test Job in the relevant editor. You can add a task ID to the item itself, but not to other items used in it (unless you edit them in their own editor).
Open the editor for the item you want to add a task ID to.
Enter a task ID in the Task ID field in the Properties View.
Save the changes
Task IDs cannot be overwritten when an item is reused.