Within Teamwork Projects, once you have created a task list you can add a milestone to this to give yourself a overarching goal to work towards.
To add a milestone, choose the 'Tasks' area of your project and on the task list you wish to add a milestone to, hover over the name of the task list and choose the 'edit' option as below:
Once this has been selected a pop up modal will appear where you can then select the 'milestone' tab. You can then choose an existing milestone from the dropdown menu or create a new one:
You can then choose the save option and the milestone will appear to the top of the task list:
For more information, see: Adding a milestone