Though mouse is the easiest way to access all of the 5pm features, sometimes keyboard can help you do some things even faster:
Add a Project and then add the Tasks to it - use "+" button on the top of the left panel.
Assign a Team to the Project or Task - in the New Project/Task popup window.
Add Messages to Projects and Tasks selected in the left panel - use the "+" button on the top of the right panel.
Add Progress Notes to Tasks to log the work progress (% of completion, time spent, etc.) - applies to tasks only.
... or you can simply close a task when it's finished using the right click on it and "Mask as Done" option in the quick menu.