Within Teamwork, you can quickly add a new message from any area of your site via the quick add menu.
Click the Quick Add ( + ) option in the main navigation menu on the left of your site. In the quick add menu, hover over More and select Milestone from the pop-out menu.
When you add a new milestone, you will need to choose which project you want to add it to first. Once selected, click Choose Project to proceed.
You can then fill out the relevant details for your new milestone. Click Add Milestone to save it to the project.
For more information, see: Using the Quick Add Menu