The free marketing calendar is the fastest and easiest way to communicate marketing plans to the whole company.  After installing the app, you get a "Marketing Calendar" tab that shows a month calendar view of your campaigns:

To set it up, simply install the app from the AppExchange. During install, grant access to all users. When installation is done, make sure you have some active campaigns with start and end dates filled in, and open the Calendar tab. 

For more, see Customizing the Free Marketing Calendar