How to mark a milestone
  1. On the right hand side of the task that you want to make a milestone, click on the “More Task Actions” icon
  1. Select the option “Mark/Un Milestone” from the menu displayed:
  1. As you can see, the task is now orange and has an orange triangle to the left, that you can click to hide or show tasks within the milestone:
  1. To place tasks under a milestone, select the corresponding tasks and click on the icon “Indent Tasks” :
  1. Now the corresponding tasks are under the milestone and by clicking the orange triangle on the left of the milestone, the tasks under it will hide: