You can assign Tasks from the Gantt or from the Board tabs.
From the Gantt tab
- Select the Project,
- You see all the Task assignments of that Project,
- Click on the blue bar, for the task assignment,
- in the Popup, click the + Add assignment button
- From the users list, select the user to assign the Task.
- Click the Done button.
Once the Tasks are assigned, you see the Task name and the user initials to whom the Task is assigned in the Gantt chart.