Once you have created a Jira Backlog item, you must enter a more detailed description.

1) Select a Backlog item by moving the mouse over the Backlog item. The Backlog item become grey (in red box).

Select Backlog Item

2) Make ONE click in Backlog item, the edit box on the right side appears

Right Side Edit Box

You can either edit directly the field or click on the ... button (red box above) to access all the fields (as shown below)

Edit Issue